This is a used engine cover or shroud for a Craftsman 21inch 6.75hp walk-behind lawn mower. The owners manual lists it as part # 37184 and calls it a Recoil Grille (black).The mower was model 917.388400. The engine was Sears Roebuck and Co. Model 143.006714, engine family YTPXS.1951BA, but it was made by either Tecumseh according to internet search of the engine family. Craftsman used both Tecumseh and Briggs & Stratton engines in their products.
It measures 10 1/2" x 7" and has 2 intact tabs that slip into the metal engine cover and a hole for a screw that secures it to the metal blower housing. It has a cutout for the starter cord and a cutaway where the oil dipstick goes. It has a scratch through the label, but otherwise is in good and servicable condition.
Please take a look at the photos and email with any questions.