The stuff is around, you just have to have some patience. Most of my stuff came from eBay. I'm a... frugal... person when it comes to 1A2, so I'm always looking for the cheapest price on this stuff. Sometimes I have to spend some time putting it back together when it shows up, but that's part of the fun for me. I got my ITT 501 from a guy on eBay who was selling some other 1A2 parts but didn't have the KSU listed. I sent him a message through eBay's messaging thing and asked if he had a KSU or if he was just selling off some old parts he had. His response was he thought nobody would ever want that crusty old thing so he didn't bother listing it. He boxed it up, along with all the 25 pair cable he could rip out of his house, and a slew of other parts and sold it to me for the price of shipping. It needed some very minor rewiring, but was otherwise ready to go. The nice thing about the 501 -and I would think they all were like this- the power supply has the ringing generator built in. The 551 series of Western Electric KSU's are awesome little packages but they didn't come from the factory with a ringing generator. You can't use the common audible ringers without the gen. The generators are getting to be a real pain in the arse to find, and you can just about forget ever finding the bracket that mounts it. Most people just strapped the generator to the interrupter with a big zip-tie and called it a day. Even when they were still being made those brackets were tough to find.
