Bill, There were two different size lines / fittings used on the Alpines. I don’t know the exact size but there is what I call a large and a small .. as you can see. Even though I knew this I have rebuilt mis-matched pairs before and felt pretty dumb when I finally realized it. As Eric suggested … you might want to rebuild your old slave depending on how pitted it is, you can hone a lot on those things and they will still work. You can buy a 1" cup at you local NAPA for a couple of bucks which might make life a little easier for you.