After much searching, and missing a 504 for $500 by a half hour a few weeks ago, passing on a nice 680 and a refurbished MDT last week, found this 504, complete with an original Sun Pulse Amplifier for doing electronic distributors, and the original cabinet, right around the corner- thanks to Chop32. Lotsa dust from sitting in a container, but everything works (needs a cover on one guage). Quite happy right now!