The Ithaca "bridge Trestle" Recoil Pad was introduced in the first 1932 Ithaca Gun Co. catalog --
1932 Ithaca Recoil pad.jpg
Pre-war the face of the pads were marked "PAT. APPL'D FOR" at the bottom of the logo --
00001. Ithaca Bridge Trestle pads.jpg
Post-war they are marked "PATENTED" as are the repros.
In 1950 Ithaca introduced the aluminum base version.
1950 Ithaca Recoil pad.jpg
For 1966 Ithaca began using this pad --
1966 ITHACA Anti-Recoil Pad.jpeg