The trick is knowing the rolling radius of your tires. Common tires you can look up on "The Tire Rack" and find out the revs/mile. That figure multiplied by the rear end ratio gives you the RPM at 60 mph.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!