In case having Campy part numbers might help in your searches:
On a full-campy bike, that piece of housing from chainstay to mech (with the proper ferrules at each end) would be part number 617 if the bike has a #621 "diver's helmet" chainstay braze-on.
For bikes with no braze-on, they made the housing stop clip #636, and it doesn't use a step-down ferrule. The housing for that came with matching "plain" ferrules at both ends, part #622
This is from Catalog 17a ('79 I think).
I don't remember ever seeing a part number for just the ferrules. I wouldn't be surprised if they did sell bags of ferrules to distributors or bike shops, but they didn't call them out in the catalog, at least not in the NR-SR era or earlier. I stopped paying attention to Campy after Record-C came out.
Oh wait here it is, in Catalog 18 ('84 I think). Plain ferrule is #619, step-down is #620. Sorry for writing the above out of ignorance, but I'm not going to delete it now, after all that typing.
![](https://cimg7.ibsrv.net/gimg/bikeforums.net-vbulletin/760x927/shifters_cables_clips_cat_18_dd7b863284b7a65e70d6e798d0dd0917900d461b.jpg)
Only the pickiest concours judge would take off points for not having the period-correct ferrules, but if you want it to look excruciatingly correct, please avoid anything made of plastic, or black or any color besides "silver" (broadly defined). Campy's were dull-plated steel, but a silver aluminum ferrule could be acceptable, at least it wouldn't make me want to hurl. They're thicker-wall though, so they don't look completely right to us old guys who grew up with
tutto Campagnolo. Please for God's sake don't use one that says Jagwire or <shudder>
Shimano on it...
Kidding! Well, mostly. I do have a small stash of actual Campy-brand cables, housings and ferrules that I keep for total period-correct builds. But for most bikes, just making it work is good enough.