11x3" backing plates??

As mentioned above , 11 “ x 2 1/2 “ and 11 “ x 3 “ Backing Plates — ARE — Different….

11 “ x 3 “ Rears ( and hence Backing Plates ) were used on Police Cars and Ambulances
And are available — USED ONLY —-

O.P. — Good Luck in the quest / search….

Yours, Craig….
yes, i know they are different then 2.5" and only available used. was just wondering
how hard they are to find these days. maybe I'm better off using the 2.5" stuff i already have.