I have seen over the years one or two vans, including jap boxes, that had a pressed metal panel put in place of the glass, seal and all. quite often the panels had a slight dish shape to give rigidity, and I know toyota at one stage did supply vans with them with a view that if people wanted glass, it was easier to change them over. i dunno....maybee I was smokin some good gear back then too, but I'm sure I saw the same being used in all Aussie panel vans, but quite rare.