Oh, wow, I remember this thread...
I've since learned a few things which I'll share.
1. The ACC HVAC system has a single port vacuum motor (Delco 15-71503 / GM #1996732 or equivalent) to operate one of the blend doors in the same place where the ECC and the cable-operated climate unit have a two port vacuum motor (Delco 15-71438 / GM 1996686 or equivalent).
2. The lever on the main HVAC enclosure of the ACC version which regulates the heat blend door operates on an entirely different pivot angle to the ECC or cable control versions. Since the lever arm is a pressed steel fitting on the blend door's axle, it's not a simple task to swap the ACC lever over from a cable one. See photos.
This is the ACC lever on the main HVAC box.
(Note: I cheated a bit and used a 940 HVAC for the photo - note the addition of a cable trough - but the lever positioning is the same)
This is the cable operated lever on the main HVAC box.
4. The 940s don't use a cable control system for their version of the non-ECC HVAC units, but rather an electronic box with vacuum controls , and what appears to be a stepper motor like the ECC unit.
4. Meaning that converting an old type ACC type HVAC to a cable control or ECC type HVAC is best done by just unbolting complete units (4 bolts on the firewall, 1 bolt inside and under the dash, and 2 bolts and a retainer under the windscreen wiper motor cowling in front of the screen) and replacing the whole HVAC as a unit than stuffing around trying to convert the ACC system to cable operation.