Original Daytona window plug

[70 sublime]

How were the original window plugs stuck into the cars ?
Were they welded in or bolted in then the seam filled the same way the 1/4 s were to the roof ? 

[odcics2]

Stitch welded along the perimeter, then leaded in, filed smooth.
3-4 blob welds holding the inner to the original Dutchman.

[Homerr]

These pics show the welds:

XX29L9B238084

XX29J9B386551