I did a lot of searching, pondering, thinking, drawing diagrams, visiting drivetrain shops, etc. I spent 3 months going through this same thing just a little while ago. I plan on running a detroit front and back, using the direct application for the D60 and the Dana 70 HD application drilled out for my D80. As far as I found out, drilling out the ring gear holes was the only change that needed to be done to make the 70HD locker fit the 80.