97 F150 Trouble
 

I own a 97 F150 4.6L. When I put it into drive it revs up to 2500 RPM before finding the gear. I am pretty shure that the tranny is out. I have read that the best thing to do is replace not rebuild. Is there any companys that make better trannys for say if I put 350 Ponies to the tires? Is the new install relitively easy? What do you all suggest?