Contrary to some rumors, the A-body cars of that era would have had 8.2's even behind the 396 with an automatic transmission.
The manual transmissions were more apt to receive the 8.875 inch 12-bolt, but not every one of them did.
The 8.5 inch came out in production in some 1972 cars, and completely replaced the 8.2 for 1973.
The 7.5 inch 10-bolt came under the Monza and Vega when it first came out.
The SS did NOT automatically come with a limited slip differential either.
These were options and had to be ordered.
This information is published in several books documenting the stories of Chevrolet's SS cars, Chevelle, Elcamino, Nova, and Camaro.
The main difference in the 8.2 and 8.5 now, is the availability of many more parts for the 8.5 since it is still in production with some improvements over the first years, and since there is much more available for it, the prices are usually quite a bit cheaper.