K30 transfer case questions

[mgarland]

I agree on the 4 speeds in the trucks, I enjoy to drive them. Do you have a part number on that adapter for the 4l80e to 205?

 

[Dooley]

At some point, I believe '81+ but not sure, all civilian 1 pc rear driveshaft 1 tons got 208's and only the 2 pc driveshaft trucks (c&c or crew cabs) still got 205's. I could be wrong on the year, it might be '85+ as there were significant changes with respect to t-cases, adapters and crossmembers.

Not true.
My 1988 V30 2 dr regular cab dually pickup had a 205 from factory with one piece driveshaft.
The Military M1008's had the 208 transfer case. The maintenance version CUCV 1031's usually had the 205's. Some M1028's also but not all of them.

 

[nvrenuf]

I read that more than a few times and accepted it as true, I was wrong.

 

[nvrenuf]

It should be noted that the military crew cabs were not "CUCV" trucks so they did not follow suite with respect to drivetrain and optional equipment.

 

[84 M1008]

I agree on the 4 speeds in the trucks, I enjoy to drive them. Do you have a part number on that adapter for the 4l80e to 205?

If the 205 has the round style flange which is identical to 208 flange you don't need an adapter from what I understand. You may need a clocking ring to put the front driveshaft on the right angle to front axle. Even though the 4l80 never had either transfer case behind it, the transmission to transfer case flanges are the same.

 

[nvrenuf]

If the 205 has the round style flange which is identical to 208 flange you don't need an adapter from what I understand. You may need a clocking ring to put the front driveshaft on the right angle to front axle. Even though the 4l80 never had either transfer case behind it, the transmission to transfer case flanges are the same.

GM did use the 4l80/205 combo one year (1991) and it does need an adapter to bolt together.

It is supposed to be possible to machine an '85+ 400/205 adapter to work for a 4l80/205 combo.

 

[84 M1008]

I'm pretty sure the TH400 pedestal will bolt up to 4l80a

 

[bucket]

I'm pretty sure the TH400 pedestal will bolt up to 4l80a

It needs some machining done for sealing or lubrication. Or both, I really don't remember.

The 4l80/241 adapter doesn't work for the 205 either, due to shift rail clearance and the lack of a shifter mount.

 

[84 M1008]

It needs some machining done for sealing or lubrication. Or both, I really don't remember.

The 4l80/241 adapter doesn't work for the 205 either, due to shift rail clearance and the lack of a shifter mount.

Yup, now I remember. My bad.

 

[nvrenuf]

The machine work is for an o-ring groove for the 4l80.

 

[mgarland]

Lots of great info here guys and I thank you for that, I made a couple of calls today and was searching for some info and parts and the buddies I called have never seen a 4l80/205 combo. 2 guys had heard of it but nobody has seen 1.
Mark

 

[bucket]

Yep, '91 V3500 (square body crew cab) only, which they didn't seem to make many of. I think at the time, many buyers must have been waiting for the new '92 models.

 

[nvrenuf]

Yep, '91 V3500 (square body crew cab) only, which they didn't seem to make many of. I think at the time, many buyers must have been waiting for the new '92 models.

I read once (maybe here) that there were only around 6k crew cabs produced and that was both 2wd & 4wd.

 

[SquareRoot]

The machine work is for an o-ring groove for the 4l80.

So where does the groove go? Is it a seal between the pedestal and rear of the trans? Just curious cuz I have a 4500 mounted Tova round pattern 205 and it's just a gasket.

 

[nvrenuf]

Yes, it's for an o-ring seal at the trans tail.

The 4l80 will not bolt directly to a 205. The 4l80 does not have the same circular pattern as your 4500, the trans case has the same 6 bolt pattern that a th400 has. The 4500 to round pattern tcase is a lucky coincidence that New Process / New Venture transitioned everything to that bolt pattern.