Most cars all have the same ratios in the 7.5/7.625" diff. Here is a rough estimate.
2.29 50% of all G-Body
2.41 30% of all G-Body
2.56 15% " " "
2.73 Less than 5%
3.08 Less than 5%
3.23 Less than 5%
3.42 Less than 5%
3.73 Less than 5%
4.10 0%
For ratios in the red, a good source of these ratios are '82 & up Camaro/Firebird and S-10's/Blazer. Look mostly for V-6 Camaro and 4 cyl in S-10. You will probably be happy.
As far as I know, the 7.5" and 7.625" interchange in the housings as long as you keep the correct carrier/bearings. Double check though.
Bear in mind, some G-Bodied cars did come with the 8.5" differential - most notably the
Grand National's.
