Yeah, it's cool! A friend of mine dropped this off for me to tinker with. His buddy had picked it up at the dump and no one knew what to expect. Last night I pulled out the old 2-prong power cord, snipped the "death cap," installed a 3-prong cord, did an enormous amount of cleaning, and plugged it in. All happy (and I'm very lucky not to have to do anything else for the moment)!
People like to claim these sound like X-Y-Z small Fender "Tweed" -- but in reality they sound like themselves. I get the point folks are trying to make: these have an excellent clean sound which gets just mwah-enough to do old-fashioned rock when you push the power full-out and control everything on your guitar. That's not my style, though, and I absolutely love the clean low-power tone this pulls.
This guy (click for link) thinks these were made by Lectrolab/Sound Products for Harmony. That sounds fair enough to me! I know it's a '61 because it's stamped April 1961 right on the chassis on the inside.