It is a Lancaster No.1.
Well, it's not here yet (just won it from Ebay:D!), but it looks good to me. I thought I'd share some pictures!
The seller said, "The blower measurements are: 15" x 14 1/2", casing 12", outlet 3" O.D., weight 38 lbs."
It needs some oiling, but I got it at an unbeleivable price of $76, so I'm happy!
I also wondered, what does the No. 1 mean (as opposed to a No. 4)?