'57-up convert/hardtop window frame material

[50Fraud]

Window frames on postwar Ford converts and Victorias are stainless-clad steel, and challenging to metal finish and/or weld.

I have been told that '57 through early '60s Ford & Merc hardtop frames are solid stainless. Can anybody confirm this, and/or provide more specific information?

Anybody know a source for such solid stainless frames, even in beat-up condition?

 

[50Fraud]

Or, does anybody have a source for stainless channel of the same dimensions as the stock window frames?