Tranny problem
 

I have a 1982 chevy k20 with a 6.2 diesel. Does this vehicle have an overdrive or 4th gear? It is shifting through 3 gears but in seems to be revving pretty high after 3rd gear and about 40 mph. I’m not sure what tranny is in it and the only number or letter I found on it was 7 or L. Any help with this would be greatly appreciated! It has 16 bolts on the transmission.

Re: Tranny problem
 

Very likely you have a TH400 so no overdrive. That is what my 84 CUCV(military K30) came with + the same 6.2 diesel. The cab has a stencil with limits of IIRC 50mph in 2WH and 30 in 4WL. 4.56 gear sets. It is not a speed demon.

Re: Tranny problem
 

Unfortunately I don’t have a tach, but in just appears to revving much higher than it has in the past when I have had it on the highway. I’m worried that I will wreck something else.

Re: Tranny problem
 

16 bolts on the pan is likely a 700r4, as if I remember right, thm350 and thm400s only had 13 pan bolts.
A 700 has a square pan, a thm350 square with one corner cut off, and a 400 has a kidney shaped pan

Re: Tranny problem
 

Here ya go:

Re: Tranny problem
 

Thanks for the pan pics and bolt counts. Concise and very useful.

To OP, if you have one of the early 700R4s, they had durability issues. Later ones had stronger internals. Not sure what year the improvements happened.

If you have lost OD, best limit your highway driving. The 6.2 doesn't like high RPMs.

Re: Tranny problem
 

Mine is number 6.

Re: Tranny problem
 

#6 is the 4 speed overdrive transmission. And ‘82 is an early one and most likely it has been gone through before. Reality is auto trans have to be rebuilt at some point.