Well Sea...If you had experience in these engines you could look at carb roller and tell its a Johnrude. You could also re-read as the OP said it was a Johnson 40HP. And yes I have the manuals but don't need them as I know the carbs are different.This is why they(carbs) have 2 different part numbers...
Description
Price
Qty
CARBURETOR ASSY.. Not Shown . 40 Models ..0439458
CARBURETOR ASSY.. Not Shown . 50 Models ..0439450