Does anyone know what the "JJ" stamping following size on back of wheel (e.g. 15X7 JJ)? Possibly the manufacturing plant? What about stamping by valve stem hole on outside of rim (e.g. AZ)?

THANKS
Chuck

I may not be right on this, but I thought that JJ was to do with the rim configuration (tubeless with rolled edge) and is really a generic code used by all manufacturers.
The AZ stamping by the valve stem is a specific code that identifies what the wheel is and what application it was used for. I alway found the manufacturer stamp inside the wheel when you remove the tire (mine says Kelsey Canada but yours might say Kelsey-Hayes). You will likely find the production date there as well, like 1/67 for January 1967 as an example.

I think AZ means Corvette.