You might contact these folks: http://lincolnoldparts.com/ . Don't let the name put you off, they also have Merc parts. 

Hi, I have quite a few 54 merc parts, but not the turn signal switch.    I don't know what you mean on the dash lens, because the turn signal indicator is built in to the cluster assembly.  If it doesn't work, it is either a bulb problem or it is not getting the power signal.  Hope this helps.   Mike

That could be a toughy..Suggest you also repost as a wanted in the "classifieds" here


Paul

Hi, I need a turn signal switch and the lens for my dash. I was told by a reliable source that the Ford switch is different from the Mercury. Looking for sources to purchase these items any suggestions is appreciated.Thanks
. Mario