Great information William, that makes me feel better about these. 3 mounting bosses in this pic. I can't go see them in person, and although I know a few people in the area, none I could expect to know anything about old wheels.
He has a good story, sounds legit how these wheels would have been passed around.
Looks like that 73 is 13, Hard to make out other side, someone told me they think Nov-Dec 13th, But you can clearly see XT. K18 is very clear on the inside both the same. Had these on my 69 Chevelle back in 72 with Goodyear raise white letter snow tires mounted on them, then onto my 71 Grand Prix.{still have}. Think they came off my brother's Motion Camaro { Yes he had a real Motion Camaro, Sold it for $1500 back in the day} You would really have to check them out.
Thanks - Andy