Not knowing how the Vintage Air mounts it would be hard to tell you which holes you need to keep.
But check out FAM Section 1, Sheet 3.19, for the use of each hole that's there. If you're not using either the fresh air or recirculating heater holes, then those could safely be closed up. For the big hole for the fresh air heater motor, you could either use the stock cover plate that's there for the recirculating heater or weld it up with a piece of sheet metal and finish it smooth.


Kevin
1951 Chevy 3100 work truck
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Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.