Mk 1 firing rest variations

[BCA]

Just for the record I have noticed the following variations the 16" division plate RH firing rests. The earliest (?) is a full 16" long and 1-5/16" tall while all the rest are only 15-1/2" long and 7/8" tall. All are 2" wide. It appears that the transition from rubber to wood occurred sometime in 1942.
Rubber versions:
No part number: 1-5/16" tall x 16" x 2" (earliest version? taller and longer than later)
TL 13003, FM Co 41: 7/8" tall x 15-1/2" x 2" wide.
CTL 13003 B: referred to in FUC-03 but I have not seen one marked with "B" suffix.
CTL 13003 C, FM Co 41: "C" is just an ink stamp, not punched
CTL 13002 C, FM Co 42, DR Co 42: "C" is punched along with rest of part number.

Wood version
CTL 13003 D, FM Co 1942.

Has anyone seen a "B" version?
Brian