Ok me and my buddy just droped a new motor in his 99 f150 that had a blew up motor in it with 250k miles on it(includein the tranny). In the process of puttin this in he drained the original fluid in it while I wasnt there. But during the installation of the tranny I was there I am 99% sure the torque convereter was as far back as it was suspose to be. I applied pressure on it and turned it and it when back 3 notches. So hopefully it isnt burned up. But neways he drove it too school the next morning It took reverse that morning. Got outta school headed home wouldnt take reverse. It goes forward in every gear but park. I really dont think the gears would be ceased up becuz the school isnt that far enough for it to get that hot I wouldnt imagne. So any ideas what might have made this occured. Improper installtion or with that many miles changein the fluid shudnt have did it could it? 99 percent sure the shifter linkage is in the right spot. Is it even possbile to put it on a wrong way if so anyway to shift gears by hand. (I guess on jackstands and see if it goes forward??? Any info or ideas or tips would be greatly Appreacitaed

 

Gotta ask, did you check the fluid level after getting it all back together and running? Did you fill the TC when you installed it? What did the fluid that was drained look like?

So many variables

 

Sounds to me like the forward clutch is not releasing. Likely burnt-up and seized.