Just to make things interesting...
I have the 4.57's in my 3/4 ton. I found one of the old GM 3 speed w/ OD trannies. With the OD engaged, it will give me a final drive ratio of 3.43:1. So, with 31" tires, I'll be just over 2200 rpm at 60mph, 2600rpm at 70mph. It seems to me that this will be right in the powerband of the engine. Plus, I still have the low gearing to be able to pull a house over.
