Putting aside the question of which type of pickup sounds better, does anybody know the history of when Trembuckers / F-spaced pickups started being produced? I am wondering in particular if my JB using guitar heroes of the early (Warren DeMartini, Steve Stevens) and late (Vito Bratta) 1980's were using JBs with standard or F spacing? I can't seem to find any vintage JB trembuckers online but plenty of standard humbucker - did F-spacing simply not exist yet? Thanks for the help!