These are the AM radio brackets for 1964 1/2 thru 66 Mustangs. Not shown is the 1966 AM 8-Track mounting bracket, C6ZA-18888-B.
The brackets are shown from the top down in all four pictures, 1964 1/2 (C4ZA-18888-A), 1965 (C5ZA-18888-A) and 1966 (C6ZA-18888-A). None have identification markings (that I could find).
Pic 1. Full length side view. Note the "short" 1 1/4 inch bend on the RH end on the top 66 type, and the longer 2 1/2 inch bend on the lower two. Also note the "rib" running up the long section on the lower 1964 1/2 type.
Pic 2. Full length top view. Same bend info as above, but note the extension of the rib on the RH end of the lower 1964 1/2 type, and the two ribs at the LH end that gets screwed to the dash, plus the bevels at the dash end.
Pic 3. Detail of the radio mounting end. The mounting hole is 0.320 in dia on all three.
Pic 4. Detail of the dash mounting end. The hole for the 1965 and 1966 brackets are deformed punched and then tapped 12-24 for screw 55592-S42. The 1964 1/2 dash end is stamped for a sheet metal screw 31498-S42, 14-10 thread.
Jim