Thanks Grigg. That's really informative.
I have a Dana 60 I want to put in for the posi, the tougher gears, the bigger brakes, and the taller ratio. It is an 8-lug and looks like it'll match my wheels, spacers notwithstanding.
I calculated with my tires (275/65R16 if I remember right...I'll have to go look again), 3.54 would give me a 75 mph cruise at around 2900 rpm. 3.73 would be around 3000 to 3100 rpm, so the 3.54's would be a more relaxed cruise.