Now don't quote me on this, but, (O'hell, quote me on it), up to about 66/67, before CBS screwed up Fender, Fender shipped their instruments with "STRAPS" (Da Da). ..... And the strap lock, as pictured on the back of the 60's bass headstock, was used for when the player would wear a tux., or (band matching)suit. ... Because, believe it or not, before punk came along, people would actually "dress up" to be on stage. The straps Fender sent out with their instrument were a long leather strap(kinky), that looped through a felt filled leather shoulder pad.(Adding to the comfort and fashion fit that todays modern musician needs for those grulling long nights under the lights). My first 66 P bass came with one in the case, though that was 30 years ago, and I don't know what happened to it. .... But, shorty after CBS took over Fender they stopped shipping out straps with the instruments, which soon meant, they didn't need to put the strop lock on the head stock. Which soon led to more corporate cut-backs, that lead Fender(CBS)into a 70's nose dive that saw the company near bankruptcy by the late 70's. ... But that a story for another day.
... Why did the bass player drive around town with a set of drum sticks on the dash of his car?
So, he could park in the handicapped zone.
Da D.