The specific carburetor on a 1984 Ford F-150 with a 5.8L (351 Windsor) 4bbl engine varied slightly depending on the exact trim level and options. Ford used several Motorcraft carburetors during that year. You won't find a single definitive answer without the specific vehicle's identification number (VIN).
However, the most common Motorcraft carburetor found on those trucks would be in the 2150 series. It's highly likely, but not guaranteed, to be a variation of that. To determine the exact model number, you'd need to check the carburetor itself for markings.
