1970 k20 transmission conversion
 

Hello everyone I'm new to the forum. My question is this I'm looking at buying a 1970 k20 (4x4) it has factory automatic transmission in it now and transfer case, could I change this transmission to a factory 4 speed and keep the transfer case or would the transfer case need to be changed moved etc? Thank you in advance for any feedback!
Posted via Mobile Device

Re: 1970 k20 transmission conversion
 

If I was going for a manual then I'd look into the NV4500 setup. Plenty of swap on this site, check out the search option.

Plan on different length driveshafts for any swap, just my guess. SM465 was the factory 4 speed though, with granny gear.

Re: 1970 k20 transmission conversion
 

The transfer case can stay in its original position. However the adapter for a 4 speed is different also the spline count of an automatic is 27 and a 4 speed is 10 I think. When doing a swap like this it would be advantageous to have a donor truck.

Re: 1970 k20 transmission conversion
 

Here is a 4 speed adapter.

Re: 1970 k20 transmission conversion
 

So the 4 speed would not work because the spline count is not correct? Or can u get a adapter to make it work with the transfer case?

Re: 1970 k20 transmission conversion
 

You would need to change your input shaft also in the transfer case. Along with coupler and adapter pictured above. The drive shafts can be reused. I just went from 4speed to automatic

Re: 1970 k20 transmission conversion
 

I recently did the same thing yes you do have to get a 4 speed to a NP 205 transfer case adapter which are not hard to find they used the same one up into the mid 80's. your transfer case is a 27 spline and your SM 465 will be a 10 spline. You and buy that adapter sleeve from Off Road Design that is 10x27 spline part# GU4011-A and you will be in business and no need to change input shaft on the transfer case.

Re: 1970 k20 transmission conversion
 

You can buy all the parts new from off road design. I don't believe the 205 adapters from ord are not cast iron like the originals are however.

Re: 1970 k20 transmission conversion
 

Thanks for the feedback!

Re: 1970 k20 transmission conversion
 

No problem and good luck and don't give up. Real men have a third pedal!! LOL