Hi Richard,
Yes, Monson 3 visited for the Annual Picnics of 1998 and 1999. In '99 we had engines 3, 9 and 10 in the yard for photo ops. The facebook post noted by Pete shows #3 running at Sheepscot in 1998. As you noted, the track only went half way down Davis grade. I have video of those trips as well. I'm sure there are folks who would like to see some of that video. If so we may put some of it on DVD for retail in the gift shop. Anyone interested?