Update:
truck has been out of service for 6 weeks now- new speed sensor (no fix), new wheel hub (no fix), new calibration (no fix). Did something with the steer angle sensor and thought that may work after the tech test drove, did one final test drive yesterday before telling me to come pick it up and the truck began engaging traction control and ABS on left turns, so they have another request into TACS. The dealer has another brand new Denali Duramax on the lot that is doing the same thing. If anyone has any info, it would be greatly appreciated. $80k experiment truck, trying so hard to remain patient, it’s getting tough though.