I remember the 4 hole front coming out about 1981.
The narrow front band often broke from over tightening
it so it lasted about one season.
It was first shown in the 16 page addendum to the #17
silver catalogue. Part number 0104007.
I also remember the b/o front hanger coming out about
the same time. They used one version for about a season
and they changed that also. Added the rearward "spike arrow"
part that went to the rear instead of a straight face section.
I have a nice 4 hole clamp on if you need one. It can be changed
out onto a b/o body if you need that.
Joe Hughes
Denver, CO