i have a 69 c20 with the eton rear end and i would like to modernize the drive train. what rear ends are being used for this swap? i have looked at some 90's and 2000's 3/4 ton from vans and trucks and wondered if they would fit with some modifications. i would like to speed up the truck and lower the RPMs to save on wear and tear on the engine as i am doing 3k rpms for 65 mph. any suggestions for a swap would be helpful...thanks.