The data tag has a column on it called "AG" which stands or Accessory Group. The '51 Henry J, being a cost-cutter, probably had the largest number of Accessory Groups available. Radios, signal lights and heaters were not part of an AG for the 1951 Henry J, they were dealer installed options. Items that were part of an AG are full wheel covers, bumper guards, vacuum boosted fuel pump, opening wing vent windows, horn ring, passenger side sun visor, trunk lid, fold down rear seat (for those cars which had a trunk lid), cigar lighter, door arm rests and a second horn. Contrary to rumor/legend, glove compartments were not part of an AG and were never optional on the Henry J. The 1951 Henry J and those '51s which were retagged as '52 Vagabonds did not have a glove compartment. All others did.
If your car is a '51 six cylinder without a trunk lid, it's AG 8. Otherwise, it could be AG 10, 17, 18, 19, 21 and maybe some others.
If you're a club member the Handbook has all the info, but that's the basics.