A TD 20 would have been seamist green. (1946-51) A TD-15, TS-15 or TS-20 would have been Dull Aluminum.
Dealers often “updated” motors and painted them the later “Sea Horse” green and sold them as used engines. There were factory bulletins that encouraged this practice to keep a shop busy in the winter months. I have found many pre-war opposed twins painted green with replacement decals that are well done, but not correct.