Remove heater blower system.

Driver side vent is independent. Biggest trick is getting the J bolt out of the pass side vent, which goes clear up and over the lip of the vent. You will need some method of plugging the cowl hole when done, or figure a way to adapt a different vent box. I put an early 'stang vent on the left one of mine because I have the new fuse/ relay/ EFI stuff "up there

The trouble with the pass side is there are no bolt/ nuts associated with the cowl opening