So I have a '88 R30 (1 ton crew cab dually). Think original camper/RV tow vehicle. Came with a 454, Turbo 400 and 4:56 rear end. Could pull a house down but was slow at top end and used a LOT of gas so last year replaced engine and transmission with a 6.2L w/ 6L80 out of a 2015 Escalade. Runs great, cruises 70-80 mph easily (not towing), but still generate about 2700 +/- rpm for that speed. Someone has suggested a higher rear gear ratio, but I'm on the fence. They think I should be able to cruise at 75 w/ about 2000 rpm (and resulting better mpg). I am not yet, but plan to pull a loaded 3 horse trailer w/living quarters or a 5th wheel RV in the future and want to make sure I'm not struggling on the low end. Any thoughts?