Looks like ORD does make a round pattern doubler for a FORD application but not a Chevy. Is your set-up a Ford version or did they make something one off for you? I'm assuming the clocking is different between Ford and Chevy round pattern?
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14bff interchange? 203/205 Doubler?
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Looks like ORD does make a round pattern doubler for a FORD application but not a Chevy. Is your set-up a Ford version or did they make something one off for you? I'm assuming the clocking is different between Ford and Chevy round pattern?
It used to be on their website.... I ordered it in 2005 and its a gen2. I bought it not knowing the difference then had to find a GM round-pattern version to make it work. I couldn't even find a GM gasket, so I used the ford round pattern gasket and stamped a hole where one of them was off, and you must pull the long input out and install the short input from a figure 8 case for it to bolt up to the doubler adapter. Its probably old and no one ordered it so its been removed from the website.
My 85 T400/205 is a round pattern. not sure on spline count, but it has a short tailshaft.
The 80 T350/205 is fig. 8. 27 spline. Long tailshaft.
I also have a Ford 203, 31 spline.
And a 77 T350/203.
I'm guessing my options are use the 350/203 and add the 205, or find a T400/203
The 80 T350/205 is fig. 8. 27 spline. Long tailshaft.
I also have a Ford 203, 31 spline.
And a 77 T350/203.
I'm guessing my options are use the 350/203 and add the 205, or find a T400/203
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What trans are you going to run? This will determine what version of range box you'll need. Just for reference, doesn't matter what range box you have you can easily swap the input without doing anything else so if you already have a 203 you would just need the proper input shaft for the trans you're going to run (along with the proper adapter from trans to t-case).
I would like to run the THM400 I have.....I could swap a new input into the 203 I have (from a 77' THM350) and that would work for the range box, then the adapter, then which 205? The 85' 205 is already bolted to the T400, but it is the round pattern, which I guess I can get an adapter from ORD to work. Are all 203 range box outputs 32 spline?
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there are many different ways to do what your trying to do (400/203/205), but you will need a complete 400-203 combo to make it work the easiest. The th400 output for a np203 adapter and input is the really short one and will need to be swapped out of your th400 or just find the complete combo.
Then the 203, that just needs a doubler kit and an input gear 32 spline unless you find the complete combo. All the ouputs on the rangebox intermediate shaft from ord should be 32 spline and you can order the 31 spliner for the ford version which you shouldn't need. (The reason I say shouldn't is because your 205(from the 400) is a long input round pattern and to make it work for the doubler, you need the short style input gear and the 31spline ford input is short and easy to find on the internet or a junkyard and you can have the (203) intermediate shaft made for 31 spline which is the same price iirc).
The 205 you will need to find out which one your going to use. If the figure eight version, you will need to order the doubler adapter accordingly same for the round pattern. All ORD gen 2 doublers use the short input. Whether its 31 or 32 doesn't matter as long as you have the corresponding parts.
If it were me, Id find the 400/203 and order a doubler kit for a round pattern if you cannot order one for a round pattern case, sell it and get a th400 32spline figure 8 case. The problem with the figure 8 case is they are the small bearing/ spline count unless it was stock behind a th400 (rare). The 1980 350/205 case you have is 27 spline and figure 8 sytle. The input bearing diameter would need to be machined bigger to fit the 32 spline input bearing. If your able to use the round case you already have, you will need an input shaft for it, either get the 32 short or the 31 ford if you cannot find the 32short. Then bolt it all together.
Then the 203, that just needs a doubler kit and an input gear 32 spline unless you find the complete combo. All the ouputs on the rangebox intermediate shaft from ord should be 32 spline and you can order the 31 spliner for the ford version which you shouldn't need. (The reason I say shouldn't is because your 205(from the 400) is a long input round pattern and to make it work for the doubler, you need the short style input gear and the 31spline ford input is short and easy to find on the internet or a junkyard and you can have the (203) intermediate shaft made for 31 spline which is the same price iirc).
The 205 you will need to find out which one your going to use. If the figure eight version, you will need to order the doubler adapter accordingly same for the round pattern. All ORD gen 2 doublers use the short input. Whether its 31 or 32 doesn't matter as long as you have the corresponding parts.
If it were me, Id find the 400/203 and order a doubler kit for a round pattern if you cannot order one for a round pattern case, sell it and get a th400 32spline figure 8 case. The problem with the figure 8 case is they are the small bearing/ spline count unless it was stock behind a th400 (rare). The 1980 350/205 case you have is 27 spline and figure 8 sytle. The input bearing diameter would need to be machined bigger to fit the 32 spline input bearing. If your able to use the round case you already have, you will need an input shaft for it, either get the 32 short or the 31 ford if you cannot find the 32short. Then bolt it all together.
Thanks Dean. I think I'm following what your saying. It would probably be easier if I had these things in front of me, and dis-assembled to see exactly what's what.
So from the list of parts I have, what would be the most cost effective/less time consuming route to take, considering the cost of replacement parts to make any particular combo work? I'm not ruling out running the THM350 either, but would prefer the THM400. If I run the THM350/203 I have now, I could change the input to the 205, get the round adapter, and be good?
So from the list of parts I have, what would be the most cost effective/less time consuming route to take, considering the cost of replacement parts to make any particular combo work? I'm not ruling out running the THM350 either, but would prefer the THM400. If I run the THM350/203 I have now, I could change the input to the 205, get the round adapter, and be good?
The most cost effective way to do the 400 is find a complete 400-203 then get a doubler kit and short input gear for your round 205.
As for your parts you already have, the most cost effective is the th350/203/205. To run the th400, its going to get expensive real quick not to mention parts hunting. But by far is the stronger option.
As for your parts you already have, the most cost effective is the th350/203/205. To run the th400, its going to get expensive real quick not to mention parts hunting. But by far is the stronger option.
Choice #1: use the TH350 with the 203 that's connected to it. Doubler kit on the back of said 203 that you spec to use the round bolt pattern. Replace the input in the 205 with the short 32 spl input gear (either 31 or 32, we carry the 32 new) and bolt it all together. The assembled Doubler will be the same length as the original 203 but you probably won't be able to use the rear driveshaft due to the ride height change from the lift you're researching.
Choice #2: use the TH400 that was mated to your round pattern 205. It should have an output shaft that sticks out about 2.5". We have an adapter plate that would let you bolt any GM 203 gearbox to it or use a 208 adapter and re-drill the front of your 203. You'll need a 32 spl input gear for the 203 to match the 32 spl output on the TH400. Then proceed like above with the Doubler process.
You can be easier on the trans with the deeper gears as long as you use the low gear and this may make the TH350 a good choice for you. It's definitely the easier way to go. If you do the entire system with the TH350 and decide to switch to a TH400 later you'll be moving everything back 3+ inches which will pretty much guarantee new driveshafts.
Points to clarify:
We do build a Doubler for the round pattern 205 as a regular item. It's not as common as the fig8 but we still do quite a few. As far as catalog confusion on this point goes, we could clarify more but I think when we wrote it I decided that the round version could be lumped in with "GM 205" and be good enough. All this is confusing enough to someone that hasn't messed with it that we should probably make everything possible as clear as possible because the subject is really complex. Trying to teach the details of all this transfer case stuff is tough!
You don't have to run modified rails to use the 3 stick shifter, the modified rails just give you access to front wheel drive only. With the 3 stick (or 2 stick on a 205 by itself) and stock rails you get all gear positions except front only. You gain the rear wheel low position that the stock shifter linkage assembly blocks you out of.
I think that's all for now. I'll check back on this before I take off tonight if you have more questions.
Choice #2: use the TH400 that was mated to your round pattern 205. It should have an output shaft that sticks out about 2.5". We have an adapter plate that would let you bolt any GM 203 gearbox to it or use a 208 adapter and re-drill the front of your 203. You'll need a 32 spl input gear for the 203 to match the 32 spl output on the TH400. Then proceed like above with the Doubler process.
You can be easier on the trans with the deeper gears as long as you use the low gear and this may make the TH350 a good choice for you. It's definitely the easier way to go. If you do the entire system with the TH350 and decide to switch to a TH400 later you'll be moving everything back 3+ inches which will pretty much guarantee new driveshafts.
Points to clarify:
We do build a Doubler for the round pattern 205 as a regular item. It's not as common as the fig8 but we still do quite a few. As far as catalog confusion on this point goes, we could clarify more but I think when we wrote it I decided that the round version could be lumped in with "GM 205" and be good enough. All this is confusing enough to someone that hasn't messed with it that we should probably make everything possible as clear as possible because the subject is really complex. Trying to teach the details of all this transfer case stuff is tough!
You don't have to run modified rails to use the 3 stick shifter, the modified rails just give you access to front wheel drive only. With the 3 stick (or 2 stick on a 205 by itself) and stock rails you get all gear positions except front only. You gain the rear wheel low position that the stock shifter linkage assembly blocks you out of.
I think that's all for now. I'll check back on this before I take off tonight if you have more questions.
Just the person we needed in this discussion. 
Clarifying on the website that a round pattern GM doubler is available would definately help people when trying to figure out if what they have can be utilized in building their doubler set-up. If i'm looking to buy something and there is plenty of info on the subject but not what i'm looking for i would suspect that it isn't available, maybe some people would ask and others not.
Clarifying on the website that a round pattern GM doubler is available would definately help people when trying to figure out if what they have can be utilized in building their doubler set-up. If i'm looking to buy something and there is plenty of info on the subject but not what i'm looking for i would suspect that it isn't available, maybe some people would ask and others not.
thanks stephen . we needed that info.
and if me running both th350 and th400 in a 1 ton rig. if i had my choice in the end and had a way to do it all right. i would chose the th350. shorter/lighter/less hp loss out the tranny/better gear ratios also.
like said take the th350/203 you have now. get the doubler kit in a round 6 pattern. get a short input and swap it. then mod the shift rails and tripple stick it. and if you can 32 spline the front over the stock 30 spline. and bolt it all in with a good trans cooler kit and temp sensor for a fan on it if to hot it will help cool. and you can get fan/cooler all in 1 kits now .
thats just me tho. others will say th400 all the way. i had a good built th350 in a 1ton with built 400sbc and it lived long and strong with 4.10 and 38 tires for years.
and if me running both th350 and th400 in a 1 ton rig. if i had my choice in the end and had a way to do it all right. i would chose the th350. shorter/lighter/less hp loss out the tranny/better gear ratios also.
like said take the th350/203 you have now. get the doubler kit in a round 6 pattern. get a short input and swap it. then mod the shift rails and tripple stick it. and if you can 32 spline the front over the stock 30 spline. and bolt it all in with a good trans cooler kit and temp sensor for a fan on it if to hot it will help cool. and you can get fan/cooler all in 1 kits now .
thats just me tho. others will say th400 all the way. i had a good built th350 in a 1ton with built 400sbc and it lived long and strong with 4.10 and 38 tires for years.
I'm reading you right on that one.
Stephen, I really appreciate your (and you other regulars too) comments, and helping me understand this multitude of options of what combo I have/want to run. When I was collecting parts (may not be done yet) I thought I had it figured out with a couple 203's and a T400/205 combo. Just hadn't schooled myself on it enough, as I thought I was a ways from doing this project, but the timing is a go right now, so I'll be getting my ducks in a row soon.
I'm sure I'll have many more questions, as this truck if pretty much a shell right now, and I would really like to have it done by May.
Once again thanks for helping the "builder challenged idiot" here.
Brett, I'm kinda thinking this might be the way to go, I know the 350 can be built to handle big block power, but at what cost to do it?, compared with a 400 pretty much stock. I'm more familiar with a 400 too, so therefore my leaning towards that trans. I can handle a 350 build though too. I will probably contact Jason Coan, he has helped me build a couple in the past and will walk me through whatever questions I have concerning that.
I'll probably rebuild a core 350 I have into a 383 for torque, although I do love rpm in an engine too. I figure with a doubler I'll have all the low end I need.
If the axle widths are the same, can I just change the spring perches, and hubs on the C&C axle to bolt into the Blazer?
I will still be adding a Detroit to it, does that mean setting up the R&P again?
use the 3/4T housing so it'll bolt up and have normal brakes. The c&c housing uses big dually only brakes and the flange is in the wrong place for common disc kits along with perches and shock mounts in the wrong place.
installing the detroit only involves re-setting the backlash and bearing preload.
installing the detroit only involves re-setting the backlash and bearing preload.
While doing some research on different doubler adapters, What are some pro's and cons of each manufacturers item.
1) how about strength
2) how about versatility...i.e. usable on different boxes w/ a change in plates (NWF).
3) price
4) service
5) availability
6) ease of use
7) variable clocking
any other points of interest as to why you like or dislike what you got?
I also see I'm going to need some bigger snapring pliers. What have you used that works good. Mine are a smaller set, that I don't think will fill this bill.
1) how about strength
2) how about versatility...i.e. usable on different boxes w/ a change in plates (NWF).
3) price
4) service
5) availability
6) ease of use
7) variable clocking
any other points of interest as to why you like or dislike what you got?
I also see I'm going to need some bigger snapring pliers. What have you used that works good. Mine are a smaller set, that I don't think will fill this bill.
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My 85' T400 is a 32 spline, the tailshaft sticks out of the housing (after adapter removed) about 1-3/8 inches.
The T400/205 is 32 spline input, and it has the round 4" adapter between them.
The 203 I have is a 27 spline from a T350, or I have a 31 splline from a C6, but that puts the shifter on the other side of the case.
I have a T400/203 adapter also.
So do I need to change the T400 output gear/tailshaft to a short 32?
I know I need to change the 203 input to a 32 spline to match the 400.
I also need to change the input to the 205 right.
The T400/205 is 32 spline input, and it has the round 4" adapter between them.
The 203 I have is a 27 spline from a T350, or I have a 31 splline from a C6, but that puts the shifter on the other side of the case.
I have a T400/203 adapter also.
So do I need to change the T400 output gear/tailshaft to a short 32?
I know I need to change the 203 input to a 32 spline to match the 400.
I also need to change the input to the 205 right.
