What's the difference in diferentials? or What ratio Horatio?

[Hilandr451]

Hey fellas,
As usual, I'm sitting here contemplating rear-ends....for my truck that is. What I've got is a C20 with a "mutt 327" power plant that I'm building for a daily driver and a tow vehicle for my 26' vintage Airstream trailer. I'm thinking of running a 700r4 in front of a 'Gear Vendors' gear splitter at stock height with 16" rims & close to stock tires.

I have a really low geared differential in it now (60MPH @ 3-1/2 grand tops) and I was wondering what gear ratio would be ideal for what I want to do with the truck. I'll be doing a great deal of highway driving, but mountain passes & campground manouvering should be considered as well.

Economy, of course, is a big concern here and I would like to be able to cruise at 75 when I'm not hooked up to the trailer - at the same time, I don't want to loose all of my torque off the line. Anybody know about ratios? Any advice would be great.