Foru Gear does yours run out of grunt on the top end.My 65 with 3.91s isnt pulling many revs in fourth.1 thru 3 is good as I shift at 6700.But once I hit 4th in the back end its loafing.Im thinking 4.30s or maybe even go back to the 4.88s.My tires are 28.5 tall.Rocky