First off I want to thank everyone who contributed to the software and all who helped with my questions. The auto steer on my JD X724 is alive and well!! It behaves much different than most mowers or tractors due to the 4 wheel steer. I turns quick and sharp.
The setup is standard - Brian’s PCB V.2 , phidgets motor, RQH100030 steer angle sensor, and the other suggested parts.
The initial reason to attempt this was to plant trees. It will get used for much more than that, mowing, spraying, watering etc. I’ll get pics and a video of it in action and post here soon.
Again, thanks to all!!