Mack R Model semi trucks are a regular sight on the highway so make yours stands out with custom, chrome, and aftermarket parts from 4 State Trucks. When you drive a Mack R Model semi truck, you're going to enjoy a fuel efficient, safe ride in a truck that's rated as one of the best in the industry. Make your rig your own - whether you need aftermarket or chrome parts like bumpers, exhaust, seating, steering or fenders, 4 State Trucks has you covered. Hit the open road in style and comfort with the best custom gear for your Mack.p of the line semi truck part you’re in search of! Shop all our Mack R Model products!