K20 transmissions
 

I'm looking to acquire a complete K20 truck or good chassis and want to know what may or may not be original and which are the ones to avoid.

Was the turbo 350 available in the K20's or was the 400 standard? Also, what manuals were available in these. Thanks in advance

Jud

Re: K20 transmissions
 

Depends on what years? I think the auto trans was available in the 70 model year. Would be a th350. (69 for blazer) Not much to avoid in these years for transmissions. They all held up decent depending on the punishment delt out...

Re: K20 transmissions
 

The Saginaw 3spd column shift was standard equipment on K/10s and K/20s.4spd manual was optional.In 1970 the TH350 became available as another option.TH400s were never offered in these trucks.

Re: K20 transmissions
 

Thank you guys! Its so hard to tell what was originally offered due to all the swapping these trucks have seen throughout the years. Why wasn't the 400 offered? Seems like a good fit for a 3/4 ton 4x4. Also, why we're on the subject, was the engine lineup the same for these as C20's? Were there any non Dana 60 rear ends used that are less than desireable? I've found a 70 CST 350/th350 with the "round" cover rearend and Dana 44 front. What axle ratios were available? Many or just a couple around 4.10? Maybe a better question is what were the differences between a K10 and K20 regarding drive train options?

I need to see if it is a NP205 but if not, are there any to avoid?

Re: K20 transmissions
 

I don't know why TH400s weren't offered,but I can say the THE 350s did all the trucks asked of it.Maybe it's that no big blocks were offered.Pretty much all TH400s were behind 396/402s weren't they?No big blocks is the only difference in available engines.Same standard engines in C and K series.
The HO52 (Corporate) is a great rear and is actually stronger than the Dana 60.You pretty much found Danas in GMCs and Corporates in Chevys.The Corporates came in 4.10,4.57,and 5.13.The Danas came with 3.54,4.11,and 4.56.I'd guess that '70 with an automatic came with 4.10s...originally.The transfer case will be a NP205.

Re: K20 transmissions
 

That's it, the TH400 was needed to handle the torque of a big block. TH350 works just fine with a small block.