tin encapsulating the rear frame?

[WaltNYC]

I stumbled upon this restoration video and noticed that as he was removing the rear frame, he had to remove what looked like a tin cover from the stubs of the existing frame. What is this? (start video at 4:05)

 

[boxster]

Removing the galvanized frame coating.

 

[mearstrae]

If you look closely the frame is made of sheeting joined by internal angle pieces, not square tubing as you would expect. Don't think this would apply to a Disco frame, unless it had a prior rear frame section replacement.

 

[WaltNYC]

so here is what mine looks like. The best term I can come up with is 'delaminating'. I'll wire brush it, use POR-15 or similar, paint, and undercoat. It seems to be early in the process.