I put my wrecked 2000 4x4 Expedition 5.4/4R100 in the shop with my 2000 4x4 F150XLT ex-cab/swb 5.4/4R70 to have engine/trans transplanted. The transmission shop in Saline Co said the 4R100 was too big for the 150. He's full of it right ? What is the difference in the install ?
I get it back from the shop and it didn't go 50mi b4 it coasted to a stop in traffic. No fluid. I threw 2qts in it to get it on the stick to no avail. Wrecker charge now. He says possibly shot taking time to fix.

 

Did you also post this in the Expedition or transmission forums? Also the 2000+ pickup forum.