I have had to remove the AC unit on several vehicles over the years. Their placement makes it a real PIA to get to the back header bolt for example. When removing the unit your left with a hole in the firewall, and another hole where the blower fits in. What I did was saw off the blower and put it back on and then get a piece of sheetmetal and form a duct that covers the remaining hole and leads to the blower. The duct only needs to be about an inch out from the firewall and you have plenty of room to get to the header bolts etc. If you look at a factory duct without AC you will see what I mean. Not very hard to duplicate.