mdauwald

Stock 275/55/20 5.3-3.73 4L60 towing 6300lb wet weight travel trailer at 65mph. usually get 8-9 mpg. Worst was 6.5 mpg with 40mph headwind.

I wonder if that's the same color as the C7 floating around? The truck pictures show it much better

I'm not sure if this can apply to our trucks because I haven't had to change a tail light bulb yet. One time in another vehicle I experienced similar havoc that was due to both filiments in a 1157 bulb fusing together. I had changed many 1157 bulbs over the years but never saw the filiments fuse together. It caused all kinds of problems with lights and signals. I'd look to see if our tailights share a single bulb for tail light and brake light. Just a wild guess