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military M1008 and NP208 problem, please help

J

jr4x4ee

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Hello!
I got myself a 1984 ex military M1008 truck 6.2D+th400+np208, D60 front and 14FF rear. It is similar to the civilian Chevy K30, but now when I am repairing it I am starting to run in to problems. I can not find a suitable rear output shaft bushing and seal for the np208 transfer case. I have gone through every known catalog at every US car parts dealer in our country and measured endless pile of bushings and seals, but just can not find the right one.
Catalogs do not even give NP208 option for the K30 and if you search for np208 from catalogs then I end up with a bushing, that is too small for my truck.
Bushing has to be internally 48mm and externally 51.5mm. Can someone help me with this matter, who has encountered the same problem? Can I even find a suitable bushing and seal, or is it a military thing only and out of production?

Thank You,
Jaak from Estonia
 
i know that my dads 82' chevy 3/4ton diesel had the th400 and 208 combo, might want to look that up and see what you can find?
 
Ya there is no difference in any of the chevrolet 208s from K10 to K30 they are all the same. Having said that any parts from any chevrolet 208 will work in any other chevrolet 208. My 87 K5 has a 208 try searching for that.

Ira
 
As I said, I have searched for every possible NP208 rear output shaft bushing combo that is possible K10, K20 you name it. So far I have ended up with bushings that have too small outer diameter.
 
Are you certain it is a 208 and not a slip yoke 205? Not sure if they had them in CUCVs or not nor am I doubting your intelligence just a thought. I have never seen any parts difference with 208s.

Ira
 
Transfer case has a plate with letters New Process Gear 208 and it is chain driven part time transfer case.

Of course there is the matter, that our dealers here have only Federal Mogul catalogs and parts regarding to that. Maybe there is some glitch in it.

Could someone measure a bushing for me on NP208 and give me the part code please?
 
I just got a part code out of an old military M1008 truck spare part catalog. It is 3978765. If I make a search on it on the rockauto.com or acdelco.com, then I end up with 88+ year NP241 application on Chevrolet. Is it possible?
Could someone measure an NP241 bushing and seal for me?

Front driveshaft is also a bit odd. It is direct replacement for K10 pickup. Odd to see such a weak shaft on Heavy Duty military equipment.
 
Front driveshaft is also a bit odd. It is direct replacement for K10 pickup. Odd to see such a weak shaft on Heavy Duty military equipment.
Click to expand...

All of GM front driveshafts are 1/2 ton, I agree does not make much sense to us but is ideal to save money on production.

Ira
 
when I got my master rebuild kit for the turbo 400 it came with a new rear output seal for the t-case, so I'm thinking the 2wd turbo 400 rear seal is probably the same thing??
 
jr4x4ee said:
I just got a part code out of an old military M1008 truck spare part catalog. It is 3978765. If I make a search on it on the rockauto.com or acdelco.com, then I end up with 88+ year NP241 application on Chevrolet. Is it possible?
Could someone measure an NP241 bushing and seal for me?

Front driveshaft is also a bit odd. It is direct replacement for K10 pickup. Odd to see such a weak shaft on Heavy Duty military equipment.
Click to expand...

I would just order the 241C bushing/seal,it will be the one you need. All the GM rear slip output housings take the same bushing and seal even the 205s.
Not sure why you are having a hard time getting the right stuff!
 
241C bushing did'nt fit, too small outer diameter, damn.
Now I am waiting for another bushing we found from the Chevrolet old original parts catalog. Same bushing has been used on Pontiac Firebird 1981 manual transmission, at least by the catalog.
 
I only see everything the others and yourself have said...the same bushing was used for the 205, 208, and 241, even the military parts manual you mention (dated 1992) backs that up.

Is it possible that the output shaft housing was somehow screwed up and re-bushed to a larger size? Not even sure the housing would accept an "overbore", but it would seem the only way to have the problem you are experiencing.

The bushings that you HAVE received, are they the right internal diameter for the driveshaft? Which leads to another question, why does it need to be replaced? Just fishing for more clues.
 
Yup, internal measures are OK. So the 208 bushing seats fine over to the tailshafts slip joint.
Outside diameter of bushing and seal are not OK.
NP208 bushing is too small for my tailshaft extension and so is the seal.

I have thought about the "custom made" bushing theory as well, but why to overbore the sealing seat in the extension? I found markings on the old bushing "fm", seemed usual GM bushing to me by looking at it. So something has to have this bushing what is used in my transfer case, but what?
 
dyeager535 said:
Which leads to another question, why does it need to be replaced? Just fishing for more clues.
Click to expand...

I see two options:
1. It needed a replacement and they had a bit larger outer diameter bushings in stock, where ever it was serviced. So it was quicker to go that way.
2. Maybe an "extra heavy duty" option, what was produced with a thicker bushing wall and larger seal outer diameter or was converted to it by some "rocketscientist" at a military base. I have heard rumors from other M1008 owners here in Europe, that the transfer case tailshaft extension might be different from the civilian model, but no one can not really tell me what did they have for spare parts.
 
Only reason I can think of that this would have happened would have been something failed, (flat towed too fast and far?) which burned up the bushing and driveshaft, eating into the housing. Seems like way too much work, but some people will spend more time fixing something that would have been better replaced.

I agree, it would be nice if someone could measure their 208 for you just to be certain, but judging from all the data, it sounds like yours is for some reason "one off".

There is always a small chance that the "aftermarket" has identified/boxed parts wrong, it's happened before, just not extremely likely.
 
What I was asking was why did YOU need to replace it, but you said you pulled it, so there was something already present. :)

Military part number for the extension housing (they call it housing main shaft) is/was 14037990. Typical GM, looks like that part number is no longer available.

I'd be surprised if it was different than the civ. part number, the 205 is infinitely stronger than the 208 and uses the same bushing.
 
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