they ALL had the single mars light, in the 90s alot was changed with 4449 including: they removed that old whistle and replaced it with 4460's whistle(witch is an original Golden State whistle)along with changing the position of the numberboard(witch was changed in the 1950's, essentially making the engine "As-recieved condition" and of course the mars light. check some photos of GS4's from the 1941, then try 1946, finally try 1957, so basically in 1976 the state it was in was a "V3" but painted in the as-built or "V1" now she has been changed from "V3" to "v1" get it now?