I have a bad 98 4r70w transmission on my 4.6l expedition and I want to put a 5.4l trans on it (I already did my research for trans fitment) but its not as easy to find a trans with the 4x4 transfercase. And it cost a bit more to find one with a t case. Is it possible to take the t case off the 98 trans and put it on a 4r70w 5.4l trans? I'm rebuilding a newer 99 4.6l engine to swap in the expedition eventually with more power hence why I want a beefier trans.

 

I don't know but I thought they were the same trans and transfer case?

 

thats what I thought but i guess the 5.4l have beefier internals

 

Nope. 4.6 and 5.4 4R70W's are identical. Torque converters are different stall speeds.

NOTE that the only direct interchange is a 4R70W out of a 1998 4x4 4.6 Expedition. Anything else will need modification. The 1998 5.4 Expys used E4OD/4R100.

Why don't you get your existing transmission rebuilt and beefed (or exchanged) by a COMPETENT shop?