I just picked up a copy of Barbara Spears' "Corvette Seatbelts 1956-1976" and found something interesting in the 1969 chapter.
In it she writes:
I know this is a mistake since the 68 came with these, but not the 69.
She goes on to write:
This is correct and what most people refer to as the chrome "shoulder belt guides" that attach to the top of the seats under the head rests (see the picture below).
However, later in the chapter she states:
THIS is the part that I find interesting. I've never seen any PLASTIC shoulder belt guides before (nor does the TIM&JG mention anything about them), and I believe this to be a mistake as well, but I've an open mind. Anyone have a late 69 with PLASTIC shoulder belt guides??
Ed
In it she writes:
A shoulder belt storage bucket was provided near the top of the seat back.
She goes on to write:
A chrome wire loop prevented the shoulder belt from retracting into the housing.
However, later in the chapter she states:
Late 1969 shoulder belts had plastic brackets on the outboard-top of seats to secure belts in position.
Ed