What is this stepdown ferule size?
 

NOTE: This is NOT my picture, sorry just googled for it cause I dont' have one handy. But that end of that derailleur cable goes into a tiny little piece on the chain stay. What size is that and where can I get a bunch so I have some spares.

http://www.raydobbins.com/ebay/bike-masi/Photo_64.jpg

Another image

http://www.raydobbins.com/ebay/bike-masi/Photo_65.jpg

Another instance where buying a Caliper to measure is a Good long term investment .

ask about 'Diver's helmet' style Braze on, ferrules at your LBS . someone in LA shops will Know.

except the Blondes..

looks like nice old camp DR housing. :thumb:

my step-down ferrule for that type of chainstay stop is just about three millimeters OD on the stepped-down portion. the ID of the ferrule end that accepts the housing is about five millimetters. i use campy non-coated housing like that on the RD of my '79 Trek with campy dropouts, or used to. now i'm using it as a short brake cable housing on a newer bike. :) expensive to buy these days. :( must be stainless, it never rusts.

It's about 2mm on my screen. HTH

Take an allen wrench and stick the one that fits in the hole , and see what size fit best

Does the ferrule need to fit the classic bare SS wound casing or modern casing? Shimano packages (or did recently) three bags of ferrules with their shop rolls of 5mm gear casing. One bag was straight 5mm ferrules, one bag was 5 to 4mm step down ones and the last bag fit Campy diving bells. Most any shop should have more then they know what to do with in their cable fittings boxes. Andy.

What did you find? Loose screws has them for a buck, 7+ for shipping.

This should work. Description: Campagnolo Stepped Gear Ferrule 4mm. It should take 4mm cable which is what the coiled wire gear cable is on old steel bikes. Or you can use modern SHIFT cable and housing which is 4mm. Brake cable housing is 5mm and probably won't fit. https://www.condorcycles.com/product...d-gear-ferrule These are extremely hard to find. Folks want $10+ each plus shipping on Ebay. This company's price as I write this, is $2.99 each and $5 US shipping. So buy some extras.

https://cimg4.ibsrv.net/gimg/bikefor...f27c5c7eeb.jpg