This is on a car I might buy and the guy said it has a 9 inch but I know a lot of people see the round pumpkin and assume it's a 9. A big selling point to me was the 9 inch rear but if it's not a 9 I might low ball him.
the top pic is a 9 inch ,the bottom pic is an 8 inch .the fill plug is packed full of grease so you cant see it .the early 9 inch is smooth on the back but that is not a 9 it is an 8 inch.
Mine is a 66. It's one inch wider per side.. I run late model Mustang wheels and it's a perfect fit.. if u wanna Retain original width have the longer side cut down. It comes with trac lok 31 spline and 373 gears and disc brakes so it's a bargain at under 200$ the old leaf perches need to b cut off and new ones welded in correct spot.. it's really ez and will take 400-500 HP + on slicks all day long
Just got an 8.8 that will be going in mine someday. 3.73 gears with trac-loc and disk brakes. 100 bucks. How can you go wrong. Also got the driveshaft for 75 bucks. Don't know if I will use it yet though.
in a 65-66 1 inch wider on each side is a lot they already have a small wheel area an inch more and tires will be a problem. using an 8.8 i would narrow it