If it's an original 440 pickup, the 5th digit should be a "D". The "A" code engines (440-3) were for industrial applications....some 1 ton duallies and bigger. The equipment sticker on the hood usually gives the major options and engine size. The emission sticker/vacuum diagram on the inside of the hood will also give engine size. Sometimes the valve cover on the engine will also have a sticker with size, tuneup, and emission info. There should also be a VIN sticker on the drivers' side door jam above the latch striker. I've also found build sheets in the usual places......taped to the back of the glove box insert, top of steering column, behind the seat back under the springs, under the carpet or rubber floor mat, and inside the door panels.