The axle tag typically has two lines of numbers and letters stamped on it. The format has changed over the years but mostly follow this sequence:.
The top line typically starts with a three-digit axle model code (or the prefix of the part number), followed by a dash, and then the suffix. The axle model codes are interchangeable, typically the suffixes are different for a revision change but the axle is still interchangeable with one having the previous suffix.
There may be a second dash and more numbers and letters on the top row if there are specifics that are unique for interchange information. Typically with just this information, you can cross reference what you need to know about the axle.
The last set of digits on the top row on the right side is the date code.
The bottom line begins with the ratio being the first set of numbers. If an L is included, it was equipped with a limited-slip differential or Traction- Lok.
The middle number is the ring gear diameter in inches, typically an 8 or 9. The last set of numbers is the vehicle plant code.
If the axle tag is missing, as most are, you need to remove the third member in order to know what ratio you have and if it has a limited-slip or not.