need help identifying a compressor

[dusterbd13]

spotted thios last night at the locust cruise in. tracked down the owner after an hour of sitting on the curb by his car, just to find out he didnt build it and had no idea what the compressor was. it appears smaller than a sanden 508, and has side exits between the moyunts. also doesnt share the square 508 mounts.
i googled the number stamped in, and got nothing. tried it at rock auto and sanden as well, and also got nothing.

it was on a small block chevy in a 65 chevelle, if that helps. all polished pullies and brackets, etc.

heres the pics i snapped:





let me know what you think.
and if you know of a retailer for it, or are one, i will order it tomorrow. just to see if it will fit where i want to stick it.

Michael