They replaced the bearings and re-greased it.
I was under the impression that you could fit a modern cartridge BB in most shells with standard threading. Anyway, if you maintain the BB regularly, it'll probably last a long, long time.
If it does break, find an LBS that has a salvage yard. There are a couple around hear that have all sorts of old BB spindles and such.
The problem may be a lack of knowledge on the part of your mechanic, or something unique about your bike. I have had a couple of bikes that are over 20 years old for which I could get new BBs for. They wouldn't be exact matches of the existing ones but they would work as well or better.
Last edited by tjspiel; 02-09-11 at 11:02 AM.