27"L X 15"W X 2" H.
No part numbers. Just the white sticker.
The previous owner said he bought it at a mustang store in Monroe, WA.
I know of this store - B&M Classic Mustang - now defunct. They bought up all the parts from the Mustang Ranch in Woodinville when they closed/were bought out. If he bought it used (most of their inventory was), it's a good chance it's an original part.
1966 Restomod/track car, 1973 Q-code Mach 1, 1997 F250 diesel, 2000 VW Beetle Rallycross car, 2010 Crown Vic (ex-City of Lakewood PD), 2015 Focus ST-2