I purchased the aluminum pumpkin and parts new from Ford Racing in 2013 and paid about $1200 for all. I think I got one of the last 28 spline Torsen diffs available. The knuckles and hubs also came from Ford Racing with a cost of ~$700. There are excellent directions on the web for setting up the gears. It wasn't that difficult for me but it does require some very accurate measuring instruments.