ing ▁to ▁the ▁use ▁of ▁block ▁letters , ▁and ▁this ▁change ▁occurred ▁sufficiently ▁close ▁to ▁res umption ▁of ▁ban jo ▁output ▁to ▁allow ▁easy ▁identification ▁of ▁pre war ▁and ▁post war ▁Gib son ▁instruments . ▁ ▁Ident ifying ▁a ▁pre war ▁Gib son ▁ban jo ▁Det erm ining ▁the ▁authentic ity ▁of ▁a ▁pre war ▁Gib son ▁ban jo ▁can ▁be ▁a ▁real ▁challenge ▁for ▁a ▁variety ▁of ▁reasons : ▁ ▁The ▁Gib son ▁company ▁produced ▁a ▁fairly ▁wide ▁variety ▁of ▁styles . ▁ ▁P rew ar ▁Gib son ▁ban jos ▁frequently ▁failed ▁to ▁conform ▁to ▁the ▁standard ▁catalog ue ▁specific ations , ▁by ▁d int ▁of ▁cost - s aving ▁measures ▁to ▁dimin ish ▁invent ories ▁of ▁excess ▁or ▁less - than - des irable ▁components , ▁thus ▁casting ▁doubt ▁on ▁the ▁devi ant ▁ban jo ' s ▁authentic ity . ▁ ▁The ▁actual ▁number ▁of ▁authentic ▁ban jos ▁is ▁relatively ▁small , ▁so ▁the ▁experience ▁of ▁exam ining ▁and ▁playing ▁them ▁is ▁limited ▁to ▁compar atively ▁few ▁individuals . ▁ ▁Dem and ▁for ▁these ▁instruments ▁is ▁high , ▁which ▁has ▁led ▁to ▁significant ▁efforts ▁toward ▁reprodu cing ▁them , ▁with ▁varying ▁degrees ▁of ▁success . ▁ ▁The ▁majority ▁of ▁these ▁ban jos ▁have ▁been ▁modified ▁in ▁some ▁way ▁by ▁their ▁own ers ▁over ▁the ▁years , ▁due ▁to ▁the ▁adjust ability ▁of ▁the ▁components , ▁changes ▁in ▁playing ▁style , ▁etc . ▁ ▁References ▁ ▁External ▁links ▁Greg ▁E arn est ' s ▁site ▁contains ▁an ▁over view ▁of ▁the ▁various