Well, I found the date ours was put together when I had to take the front door apart. Our gasket was in shreds, and before we got the thing, someone had tried to slam the door with the freezer door open, so that white inner panel on the door was cracked. I took all the screws out from around under the gasket and pulled that panel out, and there was a date stamped on the back of the white panel: MAY 18, 1949.
That white inner panel looked to be made out of some sort of molded masonite (?) type material. I siliconed the cracks in it, and it ain't real pretty, but at least it's still functional. It would be nice to find a "new" inner door panel somehow, but I'm just glad it's workin' !