I have been looking high and low for a positive traction rear end for my 1984 Camaro, seems to be really hard to find at the salvage yards when most people do not know what they are looking at. I really want 3.73 gears and I know Chevy made them for 82-92 year models. For the posi unit that chevy produced will both wheels spin in the same direction when rotated freely. I am looking for a way to find one at a salvage yard without getting the run around. Are their other ways of checking this stuff without using the axle casting numbers, because that is very difficult at the salvage yards I have been to. Thanks

There should be a parts indentification decal in the glove box or the trunk on the spare tire cover.

Look for a bunch of 3 alpha-numeric codes.

G80 - Limited Slip Differential
GT4 - 3.73 Ratio Axle
GT5 - 4.10

More than likely you are going to have to find Z28's for a Posi axle, the chances plain jane cars would have a posi are greatly reduced.