Have a 1970, (69) Shelby GT 350. How do I know if it is a 8 inch or 9 inch rear end and if it is a 28 or 31 spline rear end? Are all 69 Shelbys 31 spline 9 inch rear ends?
Guess the easy DIY would be to look at the restoration thread of the G350 on this site and see if yours matches what was shown in those pictures
Another way to identify the difference is the machined sections/surfaces of the third member housing since you can often get a deep socket on every bolt - just not always perfectly inline with the stud
Might help with a number of your questions