1950's Viking Hi-Fidelity Model RP-61 (Model B on the ID tag on the back).  It was a "built-in" unit originally.  Bought it from the original owner's grandson, who is in his 50's.

I do not know if it functions properly.  You are buying "as-is".

Check out my other auctions, as I have the matching Reel-to-Reel Tape Player (Viking Model 75) listed as well.