You get away with the gear from the nearly 33" tall tire...
Put his tire height on your truck and the 4.56 won't be as perfect with the same O.D. ratio you have in your truck is what he also has in his tremec...
Your trucks OD is .69..... his is .68.... He has probably a 25" tire and you have more like 32"
The difference is in the tire, not the trans OD ratio.
If we were talking trucks, i would bring up 4.56 or 4.88 depending on overall wants vs needs...
In this case were dealing with a shorter tire and what would be a best overall gear with the 5 speed, atleast the 3.90.. or if not then the 4.10....
