These are the stamped axle codes and gear ratios for the rear ends that were supplied with the 78-87 5th generation El Camino.

2AV - 3.08 open
2BV - 3.08 posi
2AX - 2.73 open
2BX - 2.73 posi
2AY - 2.56 open
2BY - 2.56 posi
2AZ - 2.41 open
2BZ - 2.41 posi