This was waiting for me when I arrived home from my business trip last night:
I had been searching for a Santa Fe Tk-K or Tk-M tank from Pecos River for over a decade, and I actually got this brand new one at a very reasonable price. They've recently been popping up on eBay for the first time in years, but they're going for too much there. I would have preferred the AB brake version, but the KC brake system won't be noticeable when the car is moving in a consist.