Guild were very proud of their new humbucking pickups in the early 1970s; for many years they had been using pickups produced by other companies, primarily DeArmond, but also Todd electronics and Swedish company Hagstrom. The HB-1, as shown here was in use by late 1970, and was widely fitted to just about all Guild electric guitars, Bluesbirds, Starfires, and the S series as shown here.
Guild S-90 - New Anti-Hum Pick-Ups on All Guild Guitars and Basses
This advert from December 1971 doesn't say much; letting the guitars do the talking. From Top to bottom: M75, S-50, S-90, S-100, JS bass II and JS-bass II fretless
Guild S-90 - New Solid Bodies From Guild
Early seventies Guild advert for their solid body range - featuring the new S-100, the JS basses, and the solid-body version of the BluesBird. The guitars pictured are the early versions - old styl...
Guild S-90 - Guild Electrics. Are you trying to make it without one
Advert for the S-90, S-100 SF-V (starfire) and M75 Guild six strings