Chassi had both 60's but I wanted to run a bigger rear so I found a dodge hybrid dana 80 and used the disk brakes on a GM 10 lug 80 I have had for a few years. Also the dodge 80 and my front 60 both had 3.54 gears. I am running a 203/205 combo (devorced). Nv4500 and 35's should get decent fuel mileage from the first gen 12v. With the overdrive.