What does this swap need?

[shorst97]

Am I able to swap the turbo 400 in my 86 K20 for a 700R4 in order to get some better gas mileage? What do I need for the swap? Will the drive shafts need modifications? Can I still use the 208 transfer case that is on the truck?

 

[bucket]

The 700r4 uses a smaller 27 spline output, so you would need a 208 from behind a 700r4 as well, or swap the input in your current 208. You would also need the 700r4 to 208 adapter. But, the good news is that the overall length is the same and there's no need for different driveshafts.

However, a 700r4 (even built up) really isn't a good choice for the work a K20 is meant to see. And improvements in MPG will hardly be noticeable.