Sadiq :
RE: "I have run across an odd looking Campagnolo FD.
It has a 'leg' on it with an enclosed cable stop ..."
---
Check out Campagnolo Catalog #16.
(So late 1960's - very early 1970's).
http://www.campyonly.com/
Based on your info, I believe that's the pre-Nuovo Record FD (1052/1). Chromed Bronze body rather than alloy. Flat cage, no cage holes, world logo, no lip, no circlip, no reinforced nib at the pivot point.
It wasn't that rare to see Italian 10speeds as late as 1971 with a brazed cable stop on the non-drive side of the down tube near the bottom bracket.
Typical application was to run bare cable from the dt shift lever to the brazed-on cable stop. Only a short piece of housing was used to cross over the top of the bb shell between the dt stop and the integrated fd stop.
If you were already using the old push-rod Sport or Valentino derailleur, then you already had the clips or stops to accommodate a fd w/ integrated stops. So this became an upgrade without additional clip purchases.
The 6 or 7 iterations of the familiar Nuovo Record FD were all evolutions of this starting point.
Tory Werne
Woodstock, Georgia USA