Ear plugs on the road sound just like driving the military Gamma Goat. That ugly creature had a Detroit '53 series diesel just behind the driver's head, and with only a canvas cab for noise reduction, it came with a hearing protection warning on the dash. The 'goats had a fairly short military life - they were supposed to float, the engine had to be removed to access some lube points, and they were a real PITA to climb in and out of. Most of the leftovers wound up on firing ranges as targets, with some going to the US Forest Service, and very few being surplussed to the public. Only a few wound up in military museums.