I`m not an expert on Delco signs but it doesn`t look right to me. I base my opinion on the following:
-The back of the sign is suspect in that I haven`t seen white used on the back of a tin sign. Appears to be the base color from the front.
-Hard to say from the pictures but appears to be a pretty heavy gauge of steel (thickness).
-A large (48"x8")tin sign like this, usually has the edges folded over or the sign is embossed to make it rigid.
-Appears to be void of a makers name and date code.
-Holes appear to be larger in diameter as if they would have used grommets, not correct for a tin sign more like a porcelain sign.
Dave's Garage & Memorabilia, Inc.