Alrighty then, forget everything I said. Had you confused with someone else.
I've never heard of a factory 3.90 in a 3/4 ton. Thought the majority were 4.57 'cept for some late 60's with 4.11's (and the rare 60's trucks with Dana 60). I think Art Houser makes a 3.90 for your rear but, it's bucks.
Have you thought about an overdrive transmission along with that 4.11?
I kept my 4.57 rear and installed a T5 tranny. At 75 mph, I tach at 2,500. It's pretty sweet and I get to keep my big, beefy Eaton.
-David
