I JUST did mine.
Sorry if you have done some of these, but here's my main steps...
First remove at least the passenger front seat. I'm personally getting to old to try and contort around it to get my head under the dash. Laying flat on my back on the floor is MUCH better.
If you have a console I'd remove it too. I've never been able to get my box out or back in without doing this.
There's a bracket holding the box to the dash on the passenger side of the radio.
You'll also need to unscrew the ground wire connection for the fan which is between the fan and the dash.
Then pull the wiring harness plug off the left side of the box near the heater control valve.
I took the vacuum lines of the pots and labeled them instead of trying to pull it off the controls
Hope this helps.
Bill M
65 Coronet 500 'vert
http://goo.gl/6xUS173 Dart Sport, 05 Ram 2500 CTD, 4WD, QC, LB, Laramie
14 Avenger R/T, 15 Durango R/T, 21 Model T Depot Hack