the ones that use the modern servos don't poke through the firewall like the older units.
the blower motors are more compact.
the only extra hole I had to drill was for the drain. the rest I did because it was easier for routing.
but to get it to mount I just built a plate to bolt the box to, and then ran bolts through the plate where the old blower motor mounted to the fire wall.
so the piece mounted in the factory holes.
I could adjust how high or low by mounting it differently on the plate.
it will not work with your original dash stuff though.
I thought about how to make buttons give the same resistance as pots, but it was a bit cost prohibitive and very low number production if I decided to have it made. wasn't worth the time to figure the rest of it out.