Welcome Home to AFM!
Are you sure its a "real" Magnum 500? There are tons of reproduction wheels out there, including many built decades ago that look "old". The most common give-away is that the reproductions have bright chrome spokes (you get a hard reflection in them) whereas the real thing are SATIN finish (no reflection). The outer rim is usually wrong, too - the real thing has a 1" band where the valve stem fits (the reproductions have a thin band there).
LOTS of the guys who sell these wheels use a pic of the real thing to advertise, and then deliver the repro. Beware!
Cars that came with the Magnums from the factory also had brake drums painted black.
__________________ tripleblack
"You can never be free until you let yourself go." | 
a way to decode magnum 500 wheels? 
hello all. I'm brand new to this great mustang site. lot of good stuff here!! I was just wondering how you decode these magnum 500 wheels. they are 15X7's. they are original and not repops. the digits I see are M4 and a 9 underneath. I'd appreciate any help. thank's; Gregory
