Dana axles are identified by the BOM (Bill of Material) number. The BOM number references a complete list (the BOM) of the actual parts that were used to assemble that particular axle (or ones exactly like it). The BOM number will tell you what the original application was (make, year and model), and the ratio among other things. There were a bunch of different BOM numbers just for the GM 60s that were used, depending on year, application, ratio, etc.