Quick Question

[bad6772]

I got a buddy who just finally joined here who needs a question Answered...He is unable to post until he gets approved...So i am asking for him....
He is buying a full time all wheel drive 78 3/4 ton....First he is not sure that this was even made.( as far as it being FULL TIME 4x4......Thats what he was told.........? He wants to use the 3/4 ton axles and trans (which is a 400)....And put the 3/4 ton stuff and trans on his 1/2 ton....His main concern is if his 208 transfer case will bolt up to the 400......He destroyed his 1/2 axles trans and is buying this for the the axles and trans....He has a built 454 in his 1/2 ton now......His truck is also a 78 4x4.......His name is coult454....he is a good dude....That just needs some help.......And as most of you know i be a 2wd guy so i have no idea.lol i just sent him here for the best answers.........

[Dooley]

All GM 4x4's from 74 thru 79 with V8 engine and automatic transmissions had a full time New Process Gear 203 transfer case. They are cast iron and heavy. There were problems with some of the early years but, were made more dependable in the latter years. Sometime during the 78 model year is when they updated gears and drive chain. I've had them both ,wide and narrow chain version. The 400 will bolt to the 208 if that is what the 208 come off of. Otherwise, he will have to adapt the pieces together.

[68,69 K20]

Yes, the 208 will bolt up to the 400 with the proper adapter. I run a mid 80's military Blazer for a work rig with a 400/208 combo, works great.

[1-tonmudder]

He wants to use the 3/4 ton axles and trans (which is a 400)....And put the 3/4 ton stuff and trans on his 1/2 ton....His main concern is if his 208 transfer case will bolt up to the 400......He destroyed his 1/2 axles trans and is buying this for the the axles and trans....He has a built 454 in his 1/2 ton now......His truck is also a 78 4x4.......

If both trucks are the same year model (and orig)then all he will be gaining with the front axle is a 8 lug pattern,it will be the very same axle he has now just in a 8 lug pattern.

And put the 3/4 ton stuff and trans on his 1/2 ton....His main concern is if his 208 transfer case will bolt up to the 400

If the 400 he's wanting to use had a 203 behind it the output shaft will be too short for the 208.Their are different lenths on the 400 4wd shafts(3 IIRC)
and the shaft for the 203 is the shortest.

All GM 4x4's from 74 thru 79 with V8 engine and automatic transmissions had a full time New Process Gear 203 transfer case

They used the 205's also in those years but they were not as common as the 203's.

[Dooley]

Originally Posted by 1-tonmudder

If both trucks are the same year model (and orig)then all he will be gaining with the front axle is a 8 lug pattern,it will be the very same axle he has now just in a 8 lug pattern.



If the 400 he's wanting to use had a 203 behind it the output shaft will be too short for the 208.Their are different lenths on the 400 4wd shafts(3 IIRC)
and the shaft for the 203 is the shortest.




They used the 205's also in those years but they were not as common as the 203's.

GM used the 205 transfer case in the 74-79 era behind manual transmissions. The 203 was in all V8 / automatic transmissions at this time. The 203 was an option behind the I6. Pic explains transfer case availabilty in 1978 model year.

[WyoRoadDog]

Or do you mean that someone has replaced the lock outs on the front with full time "lock ins" (don't know what it is really called).
One of the fronts I picked up for mine had these, it's just a setup that replaces the lockout and keeps the front locked in all the time. Easy to tell, as there will usually be no dial on the front, just a blank cap. Can be replaced with a lockout.

[bad6772]

Thanks everyone.....He bought the truck......I think right now his biggest concern is wheels.....He just bought a set of 35x12.50s which are on 15 inch rims.....And the donor truck has 16s....i dont know why his arse wont post here.....LOSER

[1-tonmudder]

The 15's will fit on the back but he'll have to grind the calipers some to get em to clear the front.

[WIDESIDE72]

Originally Posted by WyoRoadDog

Or do you mean that someone has replaced the lock outs on the front with full time "lock ins" (don't know what it is really called).
One of the fronts I picked up for mine had these, it's just a setup that replaces the lockout and keeps the front locked in all the time. Easy to tell, as there will usually be no dial on the front, just a blank cap. Can be replaced with a lockout.

I had the chassis and running gear out of a 73 or 74 GMC 1/2 ton 4x4 that had a 350/ 350 engine and trans. The body had rusted off and we pulled it to build a hunting buggy. It did not have any way to lock or unlock the hubs. According to the P.O. who bought it newt was this way from the factory. My understanding was companies like Warn made conversion hubs to change these out so that it could be made part time 4x4. The full time 4x4 was supposedly hard on the drivetrain and tires, since the front was locked all the time. Since it was a hunting buggy, and not road legal, we never changed it out.