The skid plates that came standard on my Ranger Lariat FX4 were steel. Same for Tacoma and Colorado, etcI agree, but they would probably put the flimsiest piece of sheet metal or maybe just a plastic shield under there and it would not do much, if anything. To a manufacturer, it’s all about squeezing every bit of fuel mileage out of a vehicle and keeping the costs down. I would prefer some steel (about 3/16” thick or aluminum, similar thickness) to help protect the underside. After looking at the pictures of the driveline from the OP, not sure a skid plate would have prevented that, but I could be wrong. I’ve had to straddle dead animals in the road before, and all I could is hope for the best. Hope he comes back with an update as to what has to be replaced to get the vibration gone!