I installed the Vintage Air Gen IV universal evaporator with an in dash control panel in place of the stock heater controls in my '68 Barracuda convertible. There is plenty of room under my '68's dash for the Gen IV, but your '66 may have a touch less. If fitment is a question, Vintage Air sells a hollow mock-up unit for trial fitment. The stock glove box liner still fit in place with the evaporator mounted under there.
I had to bend the upper mounting bracket and used nutserts to hold the upper mount. I did drill two holes in the firewall for the A/C lines and a couple more for the lower mounting bolts. The factory heater hose firewall fitting was retained, but the hole for the heater's blower motor was abandoned on my install, as the evaporator partially blocks the opening.
The Magnum serpentine belt set-up is still on my motor, so the compressor is in the factory Magnum location.
I sourced the largest R134 multi-pass condenser I could fit from Nostalgic A/C in Florida. They are great to work with for hardware, bracketry and advice.
For the dash vents, I had an interior shop near my mount custom A/C vent in the custom console and the outboard vents in the dash extension the made.
Adding some Dynamat Extreme on the firewall and floor and then insulating the firewall and floor with that double sided foil with a jute inner layer makes a huge difference in cabin comfort. The insulation really compliments the A/C install. I highly recommend anyone considering an A/C install to look into adding the insulation under their carpet and up the firewall.
It blows cold and is very effective even on 90+ degree days with the top down and it's even better with the top up.
