72 K20 4speed to 700R4 swap questions

[72 K20]

I am thinking about swapping my truck (K20) from the 4 speed trans to a 700R4 overdrive. From what I understand, the 4 speed 205 transfer case has a different input shaft than the automatic TH350 version.

I have an 84 K20 that has, I believe,the 208 TC . I have an adaptor for the 208-700R4,, and I have a 4x4 700R4.

Has anyone done this swap ?

Would I be better off finding an automatic 205 TC ?

I believe I still need an adaptor to go from the 700 to the 205 correct ?

I'm looking for ideas and input !! All reasonable suggestions are welcome !!

My ultimate goal is to have an automatic and soften the 4:10's with an overdrive !!

Have a great day everyone !! Tom

[jocko]

This is a great question, and I've only seen it before when replacing an automatic, but you pose a new twist when going from the 4-speed. You will need to replace the output of the 700R4, at a minimum - and then ensure it will mate to the 205. I believe there are a few things to consider -

engine may need to be approx 2" fwd of where it was stock (even with the adapter installed) - have read (although can't find it for a reference) that moving motor mount rear hole to the fwd motor mount hole works about right (and then re-drill for forward holes. But someone should confirm before drillin away... But, this is doable.

Good question about the 4-speed transfer case vs TH350/700R4 t-case. I don't know - hopefully someone knows that one on here.

BUT, here's what I'd do:
Call advance Adapters and tell them exactly what you're doing -
Replacing factory 4-speed woth 700R4 and mating it to the NP205 tc. It might require more than 1 kit, but might not. They will know what to do - EXCELLENT customer service to boot.

Advance Adapters adapter kit page(s): http://www.advanceadapters.com/categ...pter-kits/191/

Advance adapters OEM page: http://www.advanceadapters.com/categ...equipment/192/


a useful site thread: http://67-72chevytrucks.com/vboard/s...d.php?t=495513

[72 K20]

Jocko
Thanks for the links !! I will research them in the next few days as time allows !!

I found this thread, Post #8 describes the different input shafts.


http://67-72chevytrucks.com/vboard/s...+transfer+case

I'm going to look into the 700R4/208 Combo,,, still learning !!!
Keep the comments and info coming !!!

Take care all !!! Tom

[Chvy2NV]

Checkout BowTie overdrives. Great info there.
Posted via Mobile Device

[hevy_chevy67]

This thread should have some useful information:

http://67-72chevytrucks.com/vboard/s...79#post5559379