Kat, I think Guest has it tabbed. It's definitely an old lap steel, the "only a Gibson is......" slogan was generally used during WWII (1943-45), according to George Gruhn's Vintage Guitar Guide. Could have been one of several models that were made at the time, likely an EH-275, or EH-185, if that is a Charlie Christian pick-up as it appears to be.
Sandy