03-06 Sierra AC Control swap from Digital to Manual

[JC76251]

I have a 2005 Sierra with the digital/dual climate control and want to swap to the older style with the levers. I don't want the automatic feature and I don't like the digital temp readout or the knobs, I just want a tactile red-for-hot blue-for-cold sort of manual control.

I got the control module no problem, but the fan speed control wiring harness is different. On the old model the harness is black with 7 pins, which is just for the rheostat/fan speed knob. On the new model it's light grey and has 12 pins.

In my research I found a dozen threads of people wanting to do the reverse, most of which end with "it's more trouble than it's worth due to the various sensors and different ducting for the automatic features". Would "downgrading" be more feasable? Is there a way to splice the old fan control wires into an older harness to have the rheostat dial function properly?