i have a 93' F-150, V-8, 4x4. I had a contractor working on my house and as a favor, loaned him $$ to buy a new/used truck. Well, he didn't perform on the house and, well, you guessed, when i went to get the truck back, the tranny was in pieces. I went to a junkyard (here in Southern CA), saw the vehicle that the new (used) tranny came out of, saw it shift properly (the bronco it came out of hard right front damage) and removed properly. I'm not a mechanic, but am an engineer so I installed it myself with a knowledgeable friend. The truck won't come out of 4 low and it shifts (automatic harder than a son-of-a-gun). Kind of feels like driving a vehicle that doesn't have enough tranny fluid. The yard was kind enough to allow me to exchange, did so, but the same problem. I've taken it to the dealer(s) and they can't diagnose the problem. any suggestions>

(thanks in advance for any and all replies)