stamped date on parts?

[Nomad]

I am really curious....

I have noticed a lot, while working on my truck, that there seems to be a date stamped or part of the casting process of parts. Mostly on aluminum parts but I have seen them on the block, witches hat and other parts. It is a circle with "83" in the center and a bit of tabs around the outside of the circle, the tabs seem to have markers on them. I assume the tabs would be month or perhaps even shift or lot of parts being made.

Am I correct in assuming the circle with the "83" is the date the parts were made? If this is correct than it is obvious my truck saw a factory refurbish in or after 1983. In my Austrian build log (from 1993) it appears the truck was released from service in 1985, that or it was re-furbished by the factory in 85. Since it is in Austrian I am not entirely sure!

I sure am curious...

Cheers