69 dart GTS decode !

I was thinking that too. If it was a W25 it should be after the V codes. Probably they guy punching the plate used the W thinking it was an M.....although I don't see any wide sill moldings on the car in the photo.
Almost all 69 GTS's had the sill moldings, they were only about 3/4" wide and hard to find until the repop's came out. Most people use the Camaro moldings which are more of a bull nose than arrow shape and a little bit shorter. But quite a few were "restored" without them, probably what happened here...