Guessing 4 Gallons.
19.55 LBS empty.
19.5" Tall X 10.75 Across Bottom. If you include the spout 13.75 across.
Dull Green. Spring loaded down force on the lid. Inside liner is stainless, appear to have two or three inner seams, a vertical one, and around the bottom, maybe one at the top, see photos.
We tested and filled above the bottom seam, after an hour the bottom was still dry.
However a very very very slow drip from the spigot, but held water for an hour test.
Tiny dent in the top lid.
Has clips on side maybe to mount or tie down to a Jeep?
Not dated, maybe from the mid 1950's or earlier version.