Mack the Bulldog Radiator Cap w/under-plate

Rare/Vintage Mack the Bulldog Radiator Cap w/under-plate.

I think this is a great find! I’m hoping someone will let me know if it is or not.

This Mack Bulldog radiator cap is in great condition considering where it was found; on an old construction site in Arizona.

The dirt has been wiped away but it even still has the rubber seal underneath which is not cracked or dried out. I peeled back a little bit of the rubber seal to show the shiny metal underneath.

If someone does know anything about this radiator cap please let me know whether I should clean it and shine it up before selling it.

Research was done and the only examples found were of the Bulldog and the Cap separately but not the two together.

On the front of the Bulldog it reads: Mack Design Patent 87931

The Particulars are as follows:

Length = 6 inches
Width = 4 inches
Height = 5 ½ inches
Weight = 2 pounds 11 ounces

Any Help would be greatly appreciated.

Thanks,
~Fox