My Custom didn't have them but the one in the salvage yard did.  I removed them but haven't installed them onto mine...yet.

Yes Ray Summit !
The mystery is solved....... it supports the quarter window glass from a side to side shift.
Thanks EVERYONE!

In my body,trim & sealant assembly manual it looks to me like it maybe on page 185.
Under quarter window mechanism models 70A - 70B-70D
Figure 1 sectional view-DD item # 17
Listed as (BAC-7029876) plate assembly- quarter window side support

I am going to search vent window assemblies again

I agree with both you guys..I have 3 sets!.... I first thought they may be 55-56 parts.. and I have been searching the trim Manuel and the parts/shop Manuel.. I can't find anything..... 

I have completed my business sedan and never used these on the vent windows or the fixed quarter glass assemblies.....
I am kinda stumped!

Never owned a Fairlane.... and not sure if they belong to another model other than a 70 series model

 
   They look familiar, I think for the vent window assembly.

I've parted several Custom Tudors and I don't remember these parts in or around the quarter or door glass.  I found nothing in the FOMOCO Illustrations manual.  My quarter glass is fixed like the Business Coupes.  No help but my first impression was the lower hardware that holds the fixed quarter glass.  I used the JEGSR reproduction fixed glass hardware.

Putting together all the inner parts on my Custom 300... doors, glass, winders, tracks ,etc,etc.... I ran across these parts. and for the life of me.. cant remember where they go or what they do.
Any ideas?

Thanks

Jeff

Wow.  Almost 10k elevation, wow.  Cool. 
Glad your trip is going well. 

ditto, and to second that thought, any current reproductions of stuff they've been making for years would be on existing tooling......so, highly doubtful a major decrease in quality will be seen. I mean, it's the quality of that tooling that makes the difference, and even a lower skilled operator I would thing wouldn't have much of an effect on product.