Transfer Case Info for OEM Squarebodies

[PrairieDrifter]

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[Frankenchevy]

It could be the synchro 205. That's the only other option unless someone messed with it.

Based on what you posted, only 30 series got the synchro 205. This k2500 burb must be a 208 then…if it’s not messed with.

 

[PrairieDrifter]

Based on what you posted, only 30 series got the synchro 205. This k2500 burb must be a 208 then…if it’s not messed with.

You're right I forgot that one. Well either way it seems to have been messed with. I guess I've never seen an example of auto hubs. Only full time and manual. My 79 full time hubs look just like a moon wheel. Just a chrome dome.

 

[bucket]

Lol, the theft of ORD's info here is substantial.

I'm surprised at the lack of auto hubs out west. It seems like every 80's GM truck in Ohio originally came with auto hubs. Of course now, of the ones that are still left, they typically have manual hubs because the auto hubs were problematic.

 

[Gander]

Just thought I’d mention this here. Yesterday I got the transfer case out of a bone-stock 1988 4x4 Suburban, 350TBI/700R4, had always heard that 88-89 were NP241. Anyway, the transfer case is a NP208 that looks to be original to the truck. Just saying it looks like even in 1988 GM was putting NP208s in, maybe just using up the last of the ones they had? I’ll post pics of the tag off it later today, got to get it cleaned up.

Another thing, I’ve seen the support brace for the transfer case discussed on here before. One reason I’m replacing my case is that it’s got a chunk broken off of it at the rearmost bolt hole on the case for that brace. Still got one bolt in, but the other bolt is gone along with the aluminum around it. Anyway, I’ve seen folks on here say that not all trucks came with the brace, CUCVs didn’t come with it, etc. Just want to add that the ‘88 didn’t have the brace and looks to have never had it. Bolt holes for the brace on the transfer case don’t look to have ever had a bolt in them. So there’s that.

 

[bucket]

Just thought I’d mention this here. Yesterday I got the transfer case out of a bone-stock 1988 4x4 Suburban, 350TBI/700R4, had always heard that 88-89 were NP241. Anyway, the transfer case is a NP208 that looks to be original to the truck. Just saying it looks like even in 1988 GM was putting NP208s in, maybe just using up the last of the ones they had? I’ll post pics of the tag off it later today, got to get it cleaned up.

Another thing, I’ve seen the support brace for the transfer case discussed on here before. One reason I’m replacing my case is that it’s got a chunk broken off of it at the rearmost bolt hole on the case for that brace. Still got one bolt in, but the other bolt is gone along with the aluminum around it. Anyway, I’ve seen folks on here say that not all trucks came with the brace, CUCVs didn’t come with it, etc. Just want to add that the ‘88 didn’t have the brace and looks to have never had it. Bolt holes for the brace on the transfer case don’t look to have ever had a bolt in them. So there’s that.

Correct, the 88's still used the 208. The 241 was used in the squarebody until '89 and it was the only year for the 241 wirh a cable speedo.

Incorrect about the brace though. Your truck definitely had one to begin with.

 

[Gander]

Correct, the 88's still used the 208. The 241 was used in the squarebody until '89 and it was the only year for the 241 wirh a cable speedo.

Incorrect about the brace though. Your truck definitely had one to begin with.

My truck has a brace for sure, it’s still on it, and one of the reasons I’m replacing my Tcase is because one of the bolt holes for that brace is broken off my Tcase. It’s the 88 Suburban I got a replacement Tcase out of that looks to have never had a brace on it. Bolt holes look like there’s never been bolts threaded in. Mating surface where the brace would go is completely unmarked and aged the same as the aluminum surrounding it. Can’t say for sure it wasn’t on there from the factory but if it was it wasn’t on long and was off a LONG time.

 

[bucket]

My truck has one for sure, it’s still on it and one of the reasons I’m replacing my Tcase is because one of the bolt holes for that brace is broken off my Tcase. It’s the 88 Suburban I got a replacement Tcase out of that looks to have never had a brace on it. Bolt holes look like there’s never been bolts threaded in. Mating surface where the brace would go is completely unmarked and aged the same as the aluminum surrounding it. Can’t say for sure it wasn’t on there from the factory but if it was it wasn’t on long and was off a LONG time.

Mechanics have always been bad about putting them back on after removing them to gain access to something else. Not all mechanics of course, but many.

Oh, I forgot to mention that my '88 4x4 Suburban with 350/700/208 came with the brace.

 

[Gander]

Mechanics have always been bad about putting them back on after removing them to gain access to something else. Not all mechanics of course, but many.

Oh, I forgot to mention that my '88 4x4 Suburban with 350/700/208 came with the brace.

I see your point. The motor mount to trans cover braces were both missing off mine. Plates at the motor mounts were there, but a bolt hole on the cover was stripped out so I guess someone working on it at some point just tossed those after that bolt hole stripped. I drilled it out, helicoiled it, and replaced those. If repairing the broken hole at the transfer case brace was as easy as that I’d have already done it but the whole corner that last bolt in the brace threads into is broken off. The truck had bad motor mounts and a loose transmission mount when I got it and they’d been driving it around that way for at least a couple years as far as I can tell, I’m thinking that that’s what may have led to the break. Anyway, I’ve got it all fixed except this transfer case and fixing to have that done. When I was under that suburban I noticed it didn’t have the brace on it and jumped to conclusions maybe.

 

[vr1967]

Rear housing difference between a 91 VSS NP241 (top) vs an 89 cable NP241

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[Gander]

Any idea what the most likely factory gear ratio would be for a 1988 1/2 ton 4x4 suburban with 350TBI/700R4/NP208? I didn’t think to take a look at the glovebox sticker when I was getting this transfer case and it was raining and just a huge mess. I was planning on just swapping over my Speedo driven gear from my old case but then remembered that there’s like 3 or 4 different drive gears and also driven gears depending on what ratio you had factory and what tires? My truck came with 3.73, 15x7 aluminum rims and 31” tires stock.

 

[bucket]

Any idea what the most likely factory gear ratio would be for a 1988 1/2 ton 4x4 suburban with 350TBI/700R4/NP208? I didn’t think to take a look at the glovebox sticker when I was getting this transfer case and it was raining and just a huge mess. I was planning on just swapping over my Speedo driven gear from my old case but then remembered that there’s like 3 or 4 different drive gears and also driven gears depending on what ratio you had factory and what tires? My truck came with 3.73, 15x7 aluminum rims and 31” tires stock.

3.42 and 3.73 were most common.

 

[Gander]

3.42 and 3.73 were most common.

I went back and checked this morning and that Suburban has 3.42 gears and a G80 in the rear. Just ordered the correct drive and driven Speedo gears for the transfer case with my 3.73s along with the rebuild kit.