ID This Mercury interior light please

I found this light that is supose to be an accessory light for possibly a 49-51 Mercury interior. Anyone know anything about it? Where it would mount inthe interior?

 

All the round interior lights I ever see are on the rear roof pillar.

 

They were mounted between the rear seats just above the folding armrest on the '55 & '56 Merc Montclair.

 

Ok, thanks. So not for the 49-51 Merc?

 

I could use it in my 49, want to sell it?

 

Where would it go in a 49'? I don't own it, I just came across it on a Mercury site.