had a 49 3/4 ton and swapped my 5.17 pumpkin for a 410 out of a 1970 chevy 3/4 ton truck and it works and it took me an afternoon to do with some guidance from a friend. Now I gained about 10-12 mph and decreased my RPMs but if you have the 4.57 rear end in your truck it is my opinion that it is not worth the time or effort to gain 5-6 mph. Based on reratio charts you need to get a rear end in the 3.38 range to cruise in your truck. This is my opinion based on experience.
