I was driving on Pa Turnpike around Denver, PA, at about 75 MPH, I saw in my review mirror, what I first though was dust or smoke blowing around my truck bed. I slowed down 10-15 MPH, a small flame was visible through the rear window, between cab and bed. I immediately pulled over, put in park , turned on flashers, grabbed my phone and wallet, got out of the vehicle. opened the rear door grabbed one bag and saw flames over the cab. Flames were visibly getting larger between cab and and bed, flames were also exiting under bed and driver side rear wheel well. I walked up the turnpike about 100 feet and called 911. The truck became fully engulfed while on phone with 911. Picture labeled first picture was after 911 call, and about 5-min after stopping vehicle. Fire Company showed up 15-min. later but vehicle was already gone. Allstate Ins. has possession of truck. Truck had 25K miles and was purchased new January 2022. The truck has been maintained per manufactures specifications by Faulkner Chevrolet in Lancaster, PA. The truck had no damage ever, was never off-road, and there were no environmental issues to cause the fire. Only modifications to vehicle was a professionally sprayed in bed liner.