My dad owns Arnold trucking in powell tn. We have 5 macks, 3 tractors 2 dumptruck. Dad drives a R model mack, 350 mack with a 15spd, wet kit, 24.5s, he pulls a dump trailer every day hauling rock and sand to a concrete plant , we have a mack superliner "show" that we built frame up, 350 mack 9spd, wet kit, 24.5s. Have another 77 mack superliner show/ work truck pulling dump trailer to same concrete plant, it has 350 mack with twin turbos, 8spd, wet kit, 24.5s. Have a mack r model tri axle dumptruck with steel bed, 350 mack, 8spd. Have a mack superliner tri axle dumptruck steel bed that has a 350 mack with a cracked block, been sitting for years.