That I can understand, because they do have issues. One new thing we are seeing on Fords are issues with the front cameras on lifted trucks. Part of the camera calibration is ride height, and when a truck is lifted above the upper limit on the programming, the camera will not work properly.Here is the dealer's position where I bought my Silverado a month and a half ago-Non-GM parts and accessories are not covered under the GM New Vehicle Limited Warranty. They also may damage the vehicle, compromise it's compliance with safety standards or void the GM warranty on the vehicle itself. GM is not responsible for the consequences of installing any non-GM equipment, parts or accessories on the vehicle. A list of non-GM parts is available to you upon request.
I could either sign this or not buy the vehicle.
If you are reading the above-and you are surmising the main culprit is after market lifts and large tires-you would be correct because I asked them.
I can't tell you how many problems come up on the truck boards because of lift kits and large wheels and spacers.