I decided instead of that 411 for $325 OTD I would spend another $25 and pick up another 5906, this one with the "hooked" trigger guard. Cleaned it up last night using mostly MPro7 for a change. Came out pretty well. Let me suggest for some stubborn spots some MPro7 (or other cleaner of your choice) with a white Scotchbrite pad. A few passes with the white pad seem to add an extra layer of clean without doing any noticeable damage to the finish.
This gun is a TEYxxxx serial number so I'm thinking it's circa 1989-90, fairly early production but with Novak's low profile sites instead of the adjustable. Most of the "hooked" trigger guard 5906s I see have the adjustable rear sight with ears, except for LE trade-ins that are offered for sale from time to time online, so maybe that's the source of this particular gun on the consumer market. It appears to have been carried but shot little.