Westinghouse and Cavalier WD-20, WD-22, CD-20 and CD-22 had a bump out and notch for the lid support that other units did not have.  These units had fiberglass lid liners. These are often found broken. When repaired they are usually painted black so we had them made of black ABS material for longer life. Measures approximately 29.5 x 11.25. Note this liner is used on lids that have two holes on the sides of the lids.