I sold my Trutrak autopilot system and changed over to the Garmin G3X autopilot instead. Fortunately the GSA 28 servos fit into the same bolt holes as the old servos, so installing the new pitch servo was straightforward. And it's a bit lighter too.
The electrical connections were surprisingly not that hard to retrofit either. Of course the wiring is very different between the two systems, but the servos use a similar number of wires, so I was able to repurpose existing wiring for new tasks. The old stepper motor drive and torque sense wires became CAN and RS-232 lines – luckily I had the foresight to use shielded wire. The only new wire I had to run was a single conductor for the autopilot disconnect line; in the old system the red button was connected to the control head in the panel, whereas in the new system it connects to both the servos. The power and ground wires stayed the same.
I'll have to come up with something to do with this oddly-shaped hole in the panel, which used to be occupied by the Trutrak autopilot control head. I'll figure it out.
I haven't installed the new roll servo yet, since I need to redo some wing wiring, but the wiring that goes out through the side of the fuselage is now all prepared for the Garmin autopilot.