Here is the strange shoulder harness mounting system used on the 71's and early 72's:
The male buckle end clips onto an extremely fragile, clear plastic, do-hicky. This one actually survived 35 years in one piece. Normally you only find the screw left and no plastic do-hicky. This piece is now reproduced for about $32 a pair.
Here is the extremely stretched out elastic that once was 7" in length and is now 20" with a shortening knot halfway through it:
