The pickup itself is a traditional single coil; wound on a plastic former with Alnico magnet at the center. It has a typical DC resistance of around 7kΩ The black or white pickup cover mounts directly to the scratchplate; the bolts thread directly into the black bassplate (so no nut), with just a rubber washer providing spacing.
The pictures below are of the PU380 fitted to a 1966 Kalamazoo KG2a, 1964 and 1969 Gibson Melody Maker, and a 1966 Epiphone Granada. The underside clearly shows the magnet, around which the coil is wrapped, and some of the turns through the potting. Note the mounting bolt and rubber spacing washer in the final image; the unit was not spring-mounted, and had very limited height adjustability.
List of Gibson guitar pickups
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