With the 700R4, a set of 3.25 gears would give you a real nice cruising speed at 2000 to 2500 RPM, depending on tire size you use. I like the 9" Ford over the 12 bolt GM, mainly because it is easier to change gears. Just slide the axles out, and pop in a different center section. Even have a set of 6.33's set up on a spool for the serious Saturday night stuff. Just my 2 cents worth. The GM 12 bolt is an equally strong unit.