I own the ‘73 with the full time option from the factory. I can’t stop my transfer case from leaking. Can i remove the front drive shaft and just run the back wheels? So I don’t have to keep adding gear oil all the time?
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
1973 full time four wheel drive conversion
- Thread starter 54tide
- Start date
Yes, you can remove the front driveshaft and drive it without issues BUT that wont help the tcase leak.
If you decide to remove the shaft and it's still full time 4wd (not converted to part time) then you'll need to run the tcase in "HI LOC". Without the front shaft the regular "HI" position will send power to the path of least resistance (the missing front shaft) and the truck wont move.
I'm assuming the leak is pretty bad or you wouldn't have made this post. If you have to pull the tcase to reseal it you might consider adding a part time conversion kit to reduce parts wear and possibly gain a mpg or 2.
Btw, welcome! What part of Alabama? I'm down at the bottom.
If you decide to remove the shaft and it's still full time 4wd (not converted to part time) then you'll need to run the tcase in "HI LOC". Without the front shaft the regular "HI" position will send power to the path of least resistance (the missing front shaft) and the truck wont move.
I'm assuming the leak is pretty bad or you wouldn't have made this post. If you have to pull the tcase to reseal it you might consider adding a part time conversion kit to reduce parts wear and possibly gain a mpg or 2.
Btw, welcome! What part of Alabama? I'm down at the bottom.
Thanks for your help! I’m in Enterprise.
It leaks about a teaspoon a day. I had the best mechanic in town replace the rear transfer seal twice. He told me the seal the book calls for wasn’t even close, so he measured to locate the right seal.
Do you know if you can replace the whole system with late model stuff so parts aren’t an issue? Even if I could find an OEM tcase there would be no guarantees it wouldn’t be leaky too. I am also concerned something may be damaged/bent so no seal will seal up.
Thanks man
I'm a little rusty on tcase interchangeability. I'm assuming you probably have a th350 transmission, I think an '81+ np208 (with adapter and shifter assembly) will bolt up to your trans but you'd need to verify if the current trans tailshaft is the correct length for the swap - the 208 is a lighter aluminum unit that's very strong with a noticeably lower low range ratio (2.61 vs 2.0). Swapping to any tcase other than your np203 will force driveshaft length mods.
- Joined
- Oct 29, 2016
- Posts
- 294
- Reaction score
- 220
You're on the right track about the seal surface
If it's damaged no seal will work right
Needs to be checked
If it is, flanges/yokes are easily changed
If it's leaking from around the outside of the seal, you can change the housing.
If it's damaged no seal will work right
Needs to be checked
If it is, flanges/yokes are easily changed
If it's leaking from around the outside of the seal, you can change the housing.
With the np203 your choices are limited you can use a np205 but that is old too just stronger.
If you want to do newer go with transmission and tcase combination.
I would use 700r4 and np208 or np241 both good and better than the np203, and you get overdrive with the transmission
I put a NP-205 in a 74 K2500 I had that came with a
TH350/NP-203,that had a slipping chain...
The NP-205 bolted up OK but I had the adapter that came with it for a TH350,I do not think the NP-203 adapter would bolt up,plus it would lack the shifter boss for the pivot bolt...
I did need to find a shorter front drive shaft,but the rear fit fine,and the same crossmember worked fine too..
I still have that old NP-203,been sitting in a shed the past 20 years or so..still have the shifter too..only kept it in case I was going to make a doubler or a yard buggy with it...
I do not know for sure if the chain was loose and slipping in it,it may have just been the shifter wasn't adjusted right..truck had a 454 and if you punched it from a dead stop you'd feel and hear it skipping as it took off for a few seconds--I had the NP-20-5 so I just decided to use it..gear to gear is better than no chain,and the low range wasn't a big deal as I never use low range anyways..
TH350/NP-203,that had a slipping chain...
The NP-205 bolted up OK but I had the adapter that came with it for a TH350,I do not think the NP-203 adapter would bolt up,plus it would lack the shifter boss for the pivot bolt...
I did need to find a shorter front drive shaft,but the rear fit fine,and the same crossmember worked fine too..
I still have that old NP-203,been sitting in a shed the past 20 years or so..still have the shifter too..only kept it in case I was going to make a doubler or a yard buggy with it...
I do not know for sure if the chain was loose and slipping in it,it may have just been the shifter wasn't adjusted right..truck had a 454 and if you punched it from a dead stop you'd feel and hear it skipping as it took off for a few seconds--I had the NP-20-5 so I just decided to use it..gear to gear is better than no chain,and the low range wasn't a big deal as I never use low range anyways..
It’s a TH400. Does that mean I don’t have the 203?I'm a little rusty on tcase interchangeability. I'm assuming you probably have a th350 transmission, I think an '81+ np208 (with adapter and shifter assembly) will bolt up to your trans but you'd need to verify if the current trans tailshaft is the correct length for the swap - the 208 is a lighter aluminum unit that's very strong with a noticeably lower low range ratio (2.61 vs 2.0). Swapping to any tcase other than your np203 will force driveshaft length mods.
Th400s were available in 4x4s starting in 1977. 77-79 were the only years to find a 400/203 combo. Most 400s had either a 205, 208, or 241, with the 203 being the rarest combo with the shortest output shaft. You could have a 203. Got a picture?
This ^^
If you have a 400/203 you are stuck with a 203 as the 400 tailshaft doesn’t fit any other tcase.
Definitely post pics.
If you have a 400/203 you are stuck with a 203 as the 400 tailshaft doesn’t fit any other tcase.
Definitely post pics.
Sorry but the th400/203 was available in 73 and the 203 was the only tcase in 74
If you have a th350.... look for a np205 transfer case from a 72 k5 blazer. It was a direct bolt in and all I had to do was change my drive shaft length.
^ The NP-205 I had used came from a '72 K series,with the TH350 adapter attached ,found it in the back of a step van at a salvage yard,so what it was in originally was unknown..date tag was stamped 1972 and the adapter has a ball bearing,I think had a splined inner race for the trans output shaft..
I used a front drive shaft from a '69 K10 ,it happened to be the only year that was only 23" long,a friend had a rolling chassis that I got it from..bolted right in..the rear shaft needed no mods,it fit perfect..
If he does have a TH400 with the shortest output shaft it'll be a hunt to find a NP-203 for that setup..they didn't make that many of them..or the adapters..
I used a front drive shaft from a '69 K10 ,it happened to be the only year that was only 23" long,a friend had a rolling chassis that I got it from..bolted right in..the rear shaft needed no mods,it fit perfect..
If he does have a TH400 with the shortest output shaft it'll be a hunt to find a NP-203 for that setup..they didn't make that many of them..or the adapters..
- Joined
- Oct 29, 2016
- Posts
- 294
- Reaction score
- 220
Every rear output leak i have seen was due to a groove worn on the yoke
I've had luck seating the new seal to a slightly different position, usually deeper. To move the seal lip off the groove
If the seal bore is damaged, it's not hard to fing 203 output housings.
Plus if you don't have a 2wd conv now, you could cheaply and easily throw that in while it's apart
I've had luck seating the new seal to a slightly different position, usually deeper. To move the seal lip off the groove
If the seal bore is damaged, it's not hard to fing 203 output housings.
Plus if you don't have a 2wd conv now, you could cheaply and easily throw that in while it's apart
When you do the part time 4 wheel conversion, do you have to replace the front hubs with manual lockers?
Yes
T
tenderfoot
Guest
Jeesh, if you have a 203 and want to just stick with that they're a dime a dozen. I mean I have like 3 of em sitting in my shop. You can have one. Or heck take two. I'm not shipping 
the heavy bastage though.
the heavy bastage though.
I just did the hubs like 25 years ago. Takes the bind out.
Everything is still turning just not coupled to the front wheels.
Can’t be bothered with the lubrication issue with the part time kit.
Just my opinion.
Everything is still turning just not coupled to the front wheels.
Can’t be bothered with the lubrication issue with the part time kit.
Just my opinion.
