Okay 33,
That would be a Detroit Diesel blower from 71 or 53 series, 2 cycle diesel engine. Still has the factory colors on it. Best way to positive I.D. it would be to find the local dealer for D.D. GM used to own the company, but Roger Penske bought it about 12 or so years ago. They're now more of a 4 cycle diesel engine company. Still plenty of those older models around though. It's a little tough for me to judge the scale of the photo, but I think yours would be from a four or perhaps a six cylinder engine. They are modest out put for air volume. Back when, guys used to convert these for racing use. It took modifying the rotors, different end plates for support and drive functions, and some other minor tweeks. You would have to dig around some to come up with the parts to make it functional for a street or vintage race machine. The cost to do so would escalate to a point most likely beyond the cost of a purpose built blower such as Weiand, Littlefield, BDS, B&M, etc.