Oh my goodness….. I had to dust off some really old books for this one! Just kidding. The Dana 41 in essence is no different in set up than a newer generation axle. The stock pinion should be stamped on the head with a crazy number (+10,+9,-10,-9 or similar) which is the starting point for all your future re-gearing. Your new gear (if going to a lower gear for instance) would be stamped with a similar number; you add or subtract these numbers and compare them to a chart to determine (roughly) the amount of shim you will need for the initial set up. It’s not standardized, each axle assembly could potentially have a different setting from the same assembly line.
If your just rebuilding (not re-gearing), make note of the shim sizes and position they are in when disassembling because this will be your starting base during re-assembly. If these things are already removed and gone, you can still re-build, you will just need to rely more on the new measurements and tooth pattern and the adjustment period during set up will likely take longer.
These two links are very helpful:
www2.dana.com/pdf/AXSM-0053.PDF
www2.dana.com/pdf/AXSM-0866.PDF
