I have a GM 9.3" rear end out of a 1957 Pontiac. Casting number 522496. It has 4.30 gears (according to the "5" stamp on it) and it is open/ non-posi. I have read that there are a tough rear and that they were comparable to the Ford 9" back in the day. I see they make parts for them at http://fabcraftmetalworks.com.
Does anyone have any interest in this or know what it might be worth?