The 4001C64 and 4001C64S both apear to have Horseshoe pickups, but different part numbers in the schematics. I know that the 4001C64S has a different surround, to mimic McCartney's bass as it is today, but is the pickup actually different too?
Does the 4001C64 have a true (real magnets) horseshoe and the 4001C64S one like the one that he had replaced at the factory prior to the WIngs over America tour? or perhaps one like the retired 4001v63?