NP-208 transfer case replacement issues

[t-dub]

Howdy, I just got the t-case off my '81 Jimmy and went in to install the new one, but it doesn't fit. I'm pretty sure they're both NP-208's, they have the same cast numbers on both, but on the new one there's a ring on the inside of the input shaft side that seems to be much more shallow than the old one. It doesn't fit all the way on the shaft coming out of the transmission. Is there some kind of adapter I need for this, or am I outta luck? Help would be much appreciated!!

 

[Honky Kong jr]

Howdy, I just got the t-case off my '81 Jimmy and went in to install the new one, but it doesn't fit. I'm pretty sure they're both NP-208's, they have the same cast numbers on both, but on the new one there's a ring on the inside of the input shaft side that seems to be much more shallow than the old one. It doesn't fit all the way on the shaft coming out of the transmission. Is there some kind of adapter I need for this, or am I outta luck? Help would be much appreciated!!

Count the input splines. There are 2 different ones 27 and 32. 27 for 700r4 and 32 for the th400

 

[Honky Kong jr]

Did you measure the input shaft depth on both?

 

[t-dub]

Found my problem. There's an adapter piece on the replacement transfer case I got that's different. Dunno what exactly it's called, it's the part that's bolted on to a cross member and the chassis. Anyway I used the one off my old transfer case. Just waiting on a new gasket now!

 

[t-dub]

Thanks!

 

[HotRodPC]

Yep, you either had the wrong adapter or you have a 32 spline input when you needed a 27 spline or vice versa. I'm assuming being an 81 Jimmy, you're running a Turbo 350 so you'd need a 27 spline.

 

[Honky Kong jr]

If it's a 32 I will take it off your hands the worthless thing. Not much need for them way more 27s out there....lol

 

[HotRodPC]

If it's a 32 I will take it off your hands the worthless thing. Not much need for them way more 27s out there....lol

Very True. Hard to find a 32 spline unit though they do exist.

Hopefully you are making sure that your splines are connected up. Cuz if it is a 32 spline, you can get it to go together, but when you start it up and go to drive off you'll hear the nastiest grinding noise you ever heard. It's the 27 spline shaft spinning inside the little bigger 32 spline input just tearing up both the Tcase input and your Trans output shafts. No, I've never done it, but a Craigslister who was coming to buy a 27 spline from me and he told me about his ordeal with the wrong 32 spline shaft. Luckily he didn't tear it to bad. I put a Turbo 400 output shaft in it to make sure it had plenty of splines left, blew out the little metal dust and traded him straight across cuz I was in desperate need of a 32 spline for my A833 project.

 

[t-dub]

Thanks for the input, everyone. So I found out that the rear adapter was the problem. It's got a th350 so it's a 27 spline. The adapter or housing or whatever that was on the new t-case was about 1.5 inches too short, so it wouldn't fit the shaft coming off the transmission. Unfortunately it's way taller than the other adapter was, so I'm gonna end up having to jerry rig the cross brace to fit on the chassis. Imma be drilling some holes and putting some long bolts in to keep the thing in place. It probably would have been better to find one that fit, but I think that's how Imma do it. I'll lose a couple of inches of clearance in the process, too. I hope there's no other problems with doing it that way.

Also, I know this isn't on the same subject, but I found this little cap thing with pins in it and I have no idea what it goes too...

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[Honky Kong jr]

There are 2 different trans cross members. Older take the tall adapter newer the short. Not sure of year break down tho sorry. @HotRodPC or @bucket could decipher the break down I'm sure.

 

[HotRodPC]

Also, I know this isn't on the same subject, but I found this little cap thing with pins in it and I have no idea what it goes too...

You must be registered for see images attach

That's a U joint cup and it's needle bearings.

 

[HotRodPC]

So lets get down to the nuts and bolts of the Tcase issue. I happen to have a Th350/700r4 short adapter for NP208/NP241C that might fix your crossmember problem, or I also have the crossmember you'll need to use the tall adapter. You do have to have the correct length output shaft on the transmission. So what all did you do or change? This isn't a hard problem, just have to have the correct parts and maybe even need an adapter spacer. So was the truck originally a Th350 and NP208? I think that's rare if it was. But anyway, splain it. Where you at and what do you need?