I identified the bracket as C5ZZ-5A246-C and my note says "sec 52" on the tag. This is for a 64-66 (I assume 64) single exhaust both I-6 and V8 to the RH frame. I got this in a box of Mustang parts in an "estate sale". The rubber (cut from a white wall tire) and metal are in very good condition (some minor pitting on the exposed surface of the muffler section) although the metal has been painted semi-gloss black by the PO. I've had it for 10 years and I know he had it for at least that long as well. I'll add pictures tomorrow.
$15 plus shipping.
Send a PM if interested.
Jim
Pictures included. The second one shows the pitted surface, the fifth one shows what looks like a grind mark.
Price reduced to $10 plus shipping.