If your going to go with ford diff, go with the 9". There's much more aftermarket support for it. Waht the builder is trying to sell you on, though, is an installed bare housing, you'll have to get you're own 3rd member for it. Not really a problem, as that diff is used in almost all customs/hot rods/race cars/every Nascar racer. Unless you have the equipment to do the setup, I'd suggest getting a pre-assembled 3rd member with whatever gear you want to run. I'd also advise a TH700R4 if the car is going to be used on the street, you won't be happy with the 'Glide. One more thing, depending on what front suspension is being used, you'll want to specify that you have matching front and rear bolt patterns on the hubs, not really a big deal. Most likely, the choice will be 5 x 4 1/2", which is the common ford/MoPar pattern. That'll give the widest choice of wheels.
