While checking my rear brakes I found a marking on my wheel. is this factory Jeff?
Most likely a junkyard stock number. Every part from a salvaged car is supposed to get a stock number written onto it, usually in an ink-marker or grease crayon. Later years may or may not also include a computer-generated inventory tag as well. These inventory stock numbers (written and/or tagged) are used not only to identify it's origin in a pile or rack of parts, but also to credit the sale to the particular vehicle (profit/loss). Items such as "wheels & tires" are one of the first things removed and seperated from the "car"-cus.
NOTE: Every salvage yard uses a code system to identify parts, usually including the vehicle's make coded into the number. Some yards just use a numerical system without a vehicle make coded into the system. The system can be very basic or rather elaborate, including a vehicle's source of purchase. As I said, every yard designs their OWN coding system.
Example of a BASIC coding system:
A-731 might represent A=Chevrolet, 7=Year obtained (say 2017), 31=Consecutive number
TRANSLATION: 31st Chevrolet obtained in 2017
I shop at times on car-part.com for USED items needed to repair cars rather regularly (it avoids multiple phone calls to each and every local yard and the WAIT for a reply). Since I have my filters set to find the "closest" items to my zip-code, I see the same local yards first and have pretty much deciphered many of these yard's stock number coding. At times, I can read their stock number codes and actually leverage a price because I see how long it has been on the shelf and how readily available it may or may not be