No need to do all of that. 2 things... are your RPM's 2000 at 69 mph with stock sized tires?
OR just look at the diff tag on the diff cover. It'll say 3 73 or 3 L73 or 4 10 or 4 L10.
This is on the driver side - it tells you the type of fluid to use.
This is on the passenger side - it tells you "L73" because the bolt is covering the other 3....
