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satfix · 11-06-2020, 10:13 AM

I found a calculator: My tires are 28 inches high - with the 3.92 rear end, I need to run 3000 rpm to reach approx 65mph. In order to do that at a comfortable RPM of 2500 RPM, I'd have to drop to about a 3.07 ratio - that would get me 67MPH. 2000 RPM would run about 55MPH.

Based on what I've read, it seems I'd have to do a complete rebuild (carrier change) in my rear end to accommodate the lower ratio. Jeep differentials have this ratio, but it sounds like my best bet is to simply sell this truck and find one that has the modern drive train already installed. Hate to 'butcher' this truck as it is such a nice example of an original 52.

Thanks for the lessons and guidance - as always!

11-06-2020, 10:13 AM	#4
satfix Member Join Date: May 2020 Location: Columbia SC Posts: 31	Re: Rearend Question I found a calculator: My tires are 28 inches high - with the 3.92 rear end, I need to run 3000 rpm to reach approx 65mph. In order to do that at a comfortable RPM of 2500 RPM, I'd have to drop to about a 3.07 ratio - that would get me 67MPH. 2000 RPM would run about 55MPH. Based on what I've read, it seems I'd have to do a complete rebuild (carrier change) in my rear end to accommodate the lower ratio. Jeep differentials have this ratio, but it sounds like my best bet is to simply sell this truck and find one that has the modern drive train already installed. Hate to 'butcher' this truck as it is such a nice example of an original 52. Thanks for the lessons and guidance - as always!