63-66 floor pan steel thickness

Ive got some patching on my floor pans and googling gives me 2 thicknesses, 18 or 20 gauge thicknesses.....what were the factory pans? Anyone have any opinions? Thx

The correct is 19 gauge I believe. You could use either in my opinion. I am sure you can purchase the correct gauge metal but will most likely have to purchase a full sheet of it, but not sure.