i have a low mileage spare 1999 4.0/trans/transfer case coming from a friend.
i need a t-case for my 90 but this one is 23 spline and mine is 21.
so i want to swap the trans and t-case instead to use the 23 spline as 21 spline cases are getting a lot harder to find.

i know i can just swap out the output shafts in the t-case, so that's a last choice option.

i'm more than sure the transmission is bolt in and since i will be using the 23 spline matching case i won't have to worry about spine counts.

but i'm sure the wiring harness has changed, so is it just as simple as cutting and splicing the harness to make it work?

what about the speed sensor? what will i have to do to make that work?

 

Just swap the output shaft. You would have to swap the entire harness off the 99 trans at the least to make it work with the renix electronics.

 

You may need to disassemble the transmission to change out some of the wiring. Might be easier to swap the input gears, though