From Fretted America
"Fransch pickups (also known as Franz pickups) were used on 50's and early 60's Guild guitars. The Fransch pickup was patented by Charles Schultz (pat # 2911871, filed Sep. 14, 1954, patented Nov.10,1959). Fransch may be a pseudonym for perhaps FRANk SCHultz. Frank Schultz, was an electronics engineer, and owned a transformer, coil, etc., making company in the 50's and early 60's.
Fransch pickups really work on hollowbody Guilds, Guild freaks are really after these. The later Guild models have DeArmond pickups
Fransch pickups were manufactured in Astoria, Queens and first appeared on the 1953 Guild X-series archtops and the Aristocrat. They were very much hand-made pickups. Guild did not have exclusive rights and Franz sold pickups to other guitar manufacturers as well. They were very much handmade items, and somewhat crudely handmade at that. The bobbins were glued together, not molded, using a type of vulcanized rubber. The top and bottom bobbin pieces were cut at the corners to avoid snagging while winding. Unlike most of the day’s manufacturers, Franz had the foresight (at least for a time in the early 1950s) to create separate models for the neck and bridge, spacing the pole pieces accordingly.
Curtis Novak, who dissected many Franz pickups in preparation for his current reproduction, encountered widely varying readings from vintage models. Typical values are 4.6k for a neck pickup and 4.9k for a bridge. By 1959 DeArmond pickups started replacing the Fransch pickups on some Guilds. Original Fransch pickups are long out of production and highly sought-after which is why Curtis Novak offers accurate reproductions."