Looks like an 80's B&M 144 (144 cu. in.) for small block Chevys. It should also have a tensioner pulley to keep the 10-rib Poly-V belt tight.
Here's a short mention from a book I have, Do-It-Yourself Guide To Street Supercharging
, by Pat Ganahl
"When this book was first published in 1984, B&M Automotive had just released its low-profile, low-cost, easily installed 144 cubic inch supercharger for small-block Chevys. At the time, it was untested and, given its low-cost construction, its very low-profile manifold, and especially its light-weight extruded aluminum, Teflon-tipped rotors, I was skeptical. But B&M more than proved me wrong. As of the spring of 1998, they had sold more than 22,100 superchargers of various sizes (but all of the same design) with virtually no mechanical problems at all in street or racing applications. And their performance matches their reliability.
Like the previous Penco blower, the initial B&M 144 was obviously patterned after the GMC 4-53; it's even the same displacement. The major differences are the light weight cast-aluminum case (with integral four-barrel carb mount), end plates (with ball bearings in an oil bath in front and sealed needle bearings in back), and snout, and the very light-weight rotors cut from long, aluminum extrusions and then machined. The rotors are supported on full-length steel shafts, and are of "involute" tip design (rather than "cycloidal," or round end as in 71-series GMCs), which is in keeping with 53 series design. The single Teflon strip in each rotor tip does not "wipe" the blower case, as in a competition drag blower, but is designed to maintain a .003-.004-inch clearance so it won't wear out. If, due to over-revving, the rotors should stretch enough to rub the case walls, the Teflon provides a margin of error to prevent scuffing.
The original B&M 144 was designed to be driven at relatively high over-drive ratios (1.78:1 to 2:1) to produce a maximum seven pounds of boost on 350-400 cu. in. small blocks."
...And that's all I'm typing. Your blower and manifold look exactly like the one pictured in the book. Hope that helps.