Ugh. I've tried to reply to this twice already and erased my lengthy response. Maybe the Forum gods are trying to tell me something? Haha!
Kevin(s),
I didn't know there was a shallow long pan and a deep long pan ... so of course, I had to go the Red Book and also more Lodge catalogs! Learn something new every day! (Thanks, Kevin #2!)
The picture in the RB (page 231) of the Deep Long Pan looks just like Kevin #1's picture of his pan. Also, the RB says it was made "circa 1906-1930's" and that "this was in the line of the Blacklock Foundry".
That intrigued me, so I looked that up too! Ha! Sure enough, the Deep Long Pan was in the Blacklock catalog. I knew the picture of Kevin #1's pan also looked like the picture in the 1930's Lodge catalog (granted, the drawings in their catalogs might not look exactly like their actual pans) but I was wondering if it was listed in other catalogs ... in an attempt to date it. Well, that same Deep Long Pan picture appears in the 40's, 50's and even the 1968 catalog.
So, the best I can say is ... it could be a Lodge Deep Long Pan. As for a date, it could be from the 1910's, but could also be from the '50's or '60's.
Bottom line: it's a really cool pan and one that, if it were my dad's, I would hang on to.