ive got a 78 620 with a 3sp auto. ive put a smaller tire on it now and its not very freeway friendly. ive put feelers out for a 5 speed conversion but im not that mad at the auto. ive used the search function to gather info before asking the same questions over and over. is there a particular 720 h190 rear pumpkin thats a drop in for my truck?? i think a 3.90 would be a better solution at this point and possibly a faster and cheaper option to make my truck more texas hwy happy.