th-350 to np-203

[BigJ's K-Blaze]

I finally have some money to get a tranny now but I dont know which one is going to fit. I have a 75 k-10 with a th350 and 203 now. The th350 case cracked im buying another trans. Im lookin for something thats going to be a bolt in job. Which trannys will work. Will a th350 that was mated to a 205 case work. If so, what years am I looking for. I found a trans out of a 81 k-10... but I dont know if that will work. Thanks for any help.

-Justin

 

[BigJ's K-Blaze]

Are the bolt patterns on the 205 and 203 cases the same? Or will it require an adapter to make them fit?

 

[diesel4me]

Nope

The 205 case uses an adapter that fits only the 205--the 203 one is different..

A TH350 4x4 tranny is the same for all years,the adapter is what allows it to bolt up to different transfer cases..just about every case has its own specific adapter...

 

[spoolnaround]

I finally have some money to get a tranny now but I dont know which one is going to fit. I have a 75 k-10 with a th350 and 203 now. The th350 case cracked im buying another trans. Im lookin for something thats going to be a bolt in job. Which trannys will work. Will a th350 that was mated to a 205 case work. If so, what years am I looking for. I found a trans out of a 81 k-10... but I dont know if that will work. Thanks for any help.

-Justin

You all ready have the adapter all you need is a TH350 that is a 4x4 version. The 2wd trannie wont work unless you change the output shaft. Any shop should be able to build you a trannie if all you need is a new case (use old internals minus clutches and bands), that is the most plentiful tranny in history. I have 2 in my garage.

 

[Mad-Dog]

That is a easy swap if you have 205 adapter housing, ORD makes a drive sleeve and bearing eliminator that you will want.​

The ORD twin-stick is a nice addition as well.
I acquired a '82 blazer and used the 205 it had for my K10

 

[JK5]

First Gen GM trucks came with a 350/205 combos....
73-75' and 80' had 350/205 combos also...80' was a slip yoke.

I've used a couple 80' 350/205 combos...to replace my 350/203's.