I purchased a 904 trans and need to get as much information about it as possible before ordering parts for a rebuild. The numbers on the right side pd in the bellhousing area are: 3A293508.
The left side pan rail reads PK2681063 4387 870.
Can anybody decode this for me?

the starting #3 in 3A293508 signifies a car built in 73.

The other number is much more specific but I don't have John Kunkel's list of exactly what they mean.

That number (above the pan on the shift lever side) will specify the engine size and if it was an HP motor or not.

Thank you very much. Now I need to figure out what I can easily do during rebuild in order to increase longevity. This thing will have a manual valve body and will be used in my mild bracket Dart (less than 3000# with driver)