Can someone tell me what sort of changes the 4R70W underwent during its life? I've got a '99 LB 5.4 and I'm trying to figure out how much of a hassle it would be to install another from a '97 4.6L.

 

And are 4r70w's from 4x4's interchangable w/ 4x2's?

 

the tail on the 2wd is longer due to no transfer case installed. however they probably do swap. I believe that both are the same tranny, you'd have to swap the tail sections over.
I have the same tranny in 4x4, the 4r70w replaced the electronic controlled version of the aod around 95 and then 4r70w was replaced by 4r100 sometime in the last few years (2000/2001?)

 

The 4R70W was not replaced by the 4R100. The 4R70W was used in most of the light duty trucks and the 4R100 is used in the super duty, Lightning, Harley Davison, some of the Expeditions and F150 trucks. The 2004 F150 went to a 4R75W tranny.

The internals (clutch packs) of the 4x4 and 4x2 are interchangeable, but you would have to use the 4x2 housing and endshaft.

 

That's what I was thinking. How hard do you guys think it would be to swap that stuff out? I mean if that output shaft has a whole bunch of hardparts on it, it will be a bitch. But if it can be pulled out and then have the other put in its place, that may take a few minutes.

How about the 4.6L v. 5.4L issue? My guess is that the only real issue would be the torque converter.

 

The shaft cannot be pulled out, the tranny must be disassembled. In essence, you have to remove all the guts from the 4x4 tranny and transfer them to the 4x2 case.

 

I'm almost tempted to do this. How hard do you think that would be? Something I can do in the garage? Or would it be a major project?

 

IMHO, I think it would be a Lt Colonel project (military joke, there). The -70 has a fairly high failure rate when built by the factory.

You probably don't have the time or the special tools, and could end up with two large piles of scrap aluminum, steel, plastic, etc.

You're best off finding a used 4WD tranny, or spend the $$ to get yours rebuilt.

Good luck!