The last obvious items we see are caliper location and rotor size. Some cars had the calipers mounted in the rear, while others have it in the front. Some ('76-'79 B-bodies and '79-'81 R-bodies), had 11.75-inch rotors and others 11-inch. Some cars, the '70-'74 E-Bodies and the '70-'72 B-bodies, used the weird pin-type calipers. The spindles are the same, and simply swapped from one side to the other in certain cars to provide clearance where needed. To make the swap more trouble-free, it's recommended to install them with the calipers facing as they would have in your model, which is usually to the front.