here goes, I have an 87 F-250 with a 460, C6 auto trans with a 10.25 rearend 3.55-1. I'm currently using it as a second vehicle and I'd like to get the RPM's down on the highway as inexpensively as possible. I was thinking a new ring & pinion but but i cant seem to find anything lower then what I have. This may be a stupid question but is there another diff size that uses the same size ring & pinion set? thanks.