Got the axle pulled out and disassembled. Based on what I see so far, It appears that this was the original axle. I checked with Norm VerHage (previous owner) and he said he never made any changes to the axle.
The Housing casting date code is not 100% legible, but according to 65dartcharger on the FABO Suspension section it is J21 or Sept 21st. However, there is no way of knowing what year.