Diff Dilemna! Need opinions!

Here ya go. I'm running a stock/6 spring under an Eaton TruTrac 3.91 gear behind a 400+ horse 440 with a 727. No issues at all. The Eaton is a gear drive sure grip. Pulls the same on both sides. They claim good to 600 horse. The axles are Yukons. Do it once with a TruTrac.
Small Block