Hi Sam, got your email, really long time since I heard that model and was on this forum but let's see if I can help.
ChrisRR
Vintage stuff, from around the mid 70's
It is not a true 1A2 set but you can the line keys to work to work on a 1A2 I believe.
The original KSU for this was the TIE 10S. The set was OEMed by TIE to Executone. It was once OEMed to another company but I cannot remember who that was, I knew this because sometimes we would get a rebuilt from TIE that had their label on the bottom. It was just a more modern looking set then the tie 300's and Gray Whales. I think there was also a Executone E324 model as well.
Things that will not work without the KSU is common bell ringing (it was a tone), speakerphone and the intercom.
You may want to check with some of the guys that worked on the OLD tie (10S & 2050 systems) to see if they have a cut-down for the regular sets, it was very similar if not exact.
Sorry, I don't have a cut-down for it, My stuff went into a dumpster when I was divorced back in the late 80's.
