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Supplier details checked 2026-09-23 · Test catalog
Fits 1967-1972 Chevrolet/GMC K10, K15/K1500, K20, K25/K2500 4WD Trucks with V8 Engines, 2.50" 409 Stainless Steel
Flowmaster American Thunder Crossmember-Back Exhaust System
Crossmember-Back Design Works with Stock Manifolds or Headers, Allowing More Application Options
Three Different Tailpipe Exit Options Allow You to Tailor the Look of the Kit to Your Style
Super 44 Mufflers Deliver Increased Performance and an Aggressive to Moderate Sound Level
Mandrel-Bent Pipes Help to Maximize the Exhaust Flow for Better Performance
16-Gauge, 2.50-Inch 409 Stainless Steel Pipes add Durability and Strength
H-Pipe Style Crossover Helps Exhaust Gas Scavenging and Reduces Drone
Includes Hangers and Hardware for Installation
Lifetime Limited Warranty
Manifold down pipes and header reducers not included. Fits both long and short bed trucks.
Flowmaster 67-72 GM Truck 4WD American Thunder Crossmember-Back Exhaust System
6772 GM TRUCK 4WD AMT XMB DOSR
SYS 67-72 GM TRUCK 4
This Flowmaster American Thunder dual exhaust system is specifically designed for 1967-1972 Chevrolet and GMC K10, K15/K1500, K20, and K25/K2500 4wd trucks with V8 engines. The system is perfect for the person looking for an aggressive to moderate interior and exterior sound level. Starting at the Crossmember-Back, the exhaust comes complete with a built-in H-pipe crossover for better exhaust scavenging, all mandrel-bent 2.50-inch stainless steel tubing, a pair of Super 44 Series performance mufflers, and your choice of three tailpipe exits (Turndown behind rear tires, side exit behind rear tires, or straight out the back under the bumper). The system includes all hardware necessary for installation and is covered by our Lifetime Limited Warranty. Fits both short and long wheelbase trucks.
SYS 67-72 GM
