700r4 swap question

i have access to a rebuilt 89 model 700r4 the question is will it bolt up to a big block in a 89 crew cab dually? the truck has a th400 right now what all will i have to do to swap in the 700r4. thanks in advance guys this forum is grrrrreat

The 400 has a different length. I don't remeber witch is longer or shorter. You are going to have to change the drive shaft. The 400 is better for towing.

If I were you, i would look at getting a Gear Vendors unit for the dually. A 700R wont last very long behind a big block.

If you decide on the 700R swap, you will have to modify your trans x-member. Should be easy to do.

the 700r4 will last behind a 454 in a dually. they're not a high output motor by any means in those year trucks.

I would be conserned about the over all lenght measurements though.

th350 has a 6 or 9 inch tailshaft,9 inch tailshaft is the same over all length as a 700. x member does need to be moved back.not sure about the th400, measure the tailshaft housing on the 400