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? for people with a th350/np208

N

nicks

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I have a th350/203 that I want to use the trans and mate it to a 241. I know that in the early 80s some k5s came with a 350/208 setup from the factory. My question is, from what I have found these usually had a tall adapter, is this correct? Also, is the tail shaft length the same on 350/203? If someones has a tail shaft measurement for a 350 that bolts to a 208 please post it as it would answer most of my questions. I was almost done drawing up a adapter on solidworks, when I realized some th350s came stock with a 208. I have seen tall and short adapters advertised as interchangeable between 700/208 and 350/208, yet believe that the 700 has a longer tail shaft.
 
AFAIK the TH350 used with a 208 has a longer stick out than a TH350 used with a 203. I also believe that there were short and tall adapter used.
 
Do you see any reason why I couldn't just cnc out an adapter similar in width and design to the 203 adapter? That should give me plenty of spline engagement without having to strip the transmission to change the tail shaft. Judging from pictures I have seen the stock 208 adapter is like ~2-3" long, which leads me to believe that if I use an adapter that is ~1" shorter than that length it would adjust for the ~1" shorter tailshft used in 350/203 applications. The 241 should be here in a couple of days to take some more specs. I have lurked here for quite some time and read many of your posts, what kind of automotive machinist are you?
 
That's not going to work as the stick out length on a TH350 for a 203 is something like 7/8" but a TH350 for a 208 is more like 3" or so and IIRC the input gear on the 208 is longer than a 203 input.
 
Do you mean that the input gear on a 208 protudes farther from the front of the case than the input gear on a 203?
 
4X4HIGH said:
That's not going to work as the stick out length on a TH350 for a 203 is something like 7/8" but a TH350 for a 208 is more like 3" or so and IIRC the input gear on the 208 is longer than a 203 input.
Click to expand...
And by the way the shaft on the 208 version sticks out more like 4-6"
The adapter is 5" thick and I have one here.
The adapter for the 700/208 is 4" thick.
So yeah the th350 you have will not work without another shaft or the stub shaft from AA.
:o
 
sorry to hijack but my question is relevant. is there a thickness difference between the short and tall 350/700 to 208/241 adapter. My truck currently has a 700 with a 241 and the tall adapter. I bought a short adapter so that when i clocked the t-case up I could achieve a more flat bottom.

I already have the adapter but it looks just like this one.
http://cgi.ebay.com/ebaymotors/Adapter-Plate-700R4-TH350-to-NP-208-241-GMC-Chevy_W0QQcmdZViewItemQQcategoryZ46104QQihZ020QQitemZ300115898695http://myspacetv.com/index.cfm?fuseaction=vids.individual&videoid=3125645

the one that is currently in the truck looks like this.
http://cgi.ebay.com/ebaymotors/Adapter-Plate-TH350-700R4-to-NP-208-Chevy-Truck_W0QQcmdZViewItemQQcategoryZ46104QQihZ020QQitemZ300106181890

I am asking about the distance between the back of the trans and the front of the t-case. I would just measure it but I store my truck far from where I live and don't get out there often.
 
When my 241 shows up I'll slide it on the tranny and see how much spline engagement it has when it is backed off from bottoming out ~5/8". If my assumptions are correct then I would have ~1-3" of space between them for an adapter, which I already have almost done on solidworks. This is if a 241 has the same amount of input shaft stickout as a 208. So I will basically end up with an adapter that is similar to a 350/203 adapter in basis shape, but round 6 instead of figure 8, and is slightly thicker. Does this sound about right? If anyone else is interested in doing this contact me, because once I have it drawn up and a sample cut and fitted, material is cheap to make more. If this is off in left field speak up, but I have a 350 that is rebuilt and would rather machine an adapter than tear it down and buy and change the tailshaft.
 
If you need the shorter output, there's no need to disassemble the trans. The shaft diameter and spline cut are long enough for all configurations. If the shaft is too long, cut it. Don't forget to bevel the new end; a disc sander works well for that, and it doesn't have to be precise, just enough to feed into the T-case.:D
 
According to what I have been told I need the long tail shaft to make this bolt up with factory parts.
 
nicks said:
According to what I have been told I need the long tail shaft to make this bolt up with factory parts.
Click to expand...
If you've never done a TH350 before, or if you don't have the book, the one by Ron Sessions will take you through it, step by step. Good luck.:D
 
It is just that the trans is sitting in a bag on a shelf with a fresh rebuild and for me it is easier just to whip out an adapter than it is to tear it down to change to a long shaft. Or just keep it for one of my other projects (I think they are reproducing) and find a 700.
 
nicks said:
It is just that the trans is sitting in a bag on a shelf with a fresh rebuild and for me it is easier just to whip out an adapter than it is to tear it down to change to a long shaft. Or just keep it for one of my other projects (I think they are reproducing) and find a 700.
Click to expand...
Pictures?
 
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