Hello.
I have a question regarding specific lamp date numerals for General Electric slimline lamps from around mid-late 1950's to 1970's (any year)

Thanks!

 I  know  1960s to 1993

  Etch start  With a dash mark for Each letter of General Elc.
   First letter of each year G is 1 and C is 0.  It runs in a 10 year
  Cycle.   There  are details u need pay attention to.   Such as 1
 Hole punch end caps from  1960s.   Two hole punching in end caps and inside etch  and Outside etch details.   Late 70s to
 1993 would have outside etch,  70s  lamp generally  have inside
 Etch with  two hole punching.  While 60s  lamp have inside etch
  1 hole punching.   Now 1950s   early 60s  F40s  would of 3 and 3 plus etching  for  the CW , WW and Daylights.   1950s  it be cool white standard,  warm white standard  era