I got lucky, a friend gave me a 78 Firebird and it turned out to have a 10 bolt posi in it, I'm haven't checked out the ratio yet but who cares right now. I installed the Chassis Engineering Kit and it was real straight forward. The hardest part, as usual, was getting rid of all the old brackets. On the forward mount you use some of he original bolt holes and in the rear all the old holes. The kit does center the rear end in the wheel well and drops the truck 4". Add lowering blocks and you can get it where you want it. As soon as I get it rolling I'll get a side view to show rake. Also, I will add a rear sway bar soon so I can see where I'll put the fuel tank.