EXCEPT Vehicles with Dual Rear Wheels. This dual 2.75" diameter into single 3" diameter Cat-Backâ„¢ system was developed for use on F-250 and F-350 Super Duty (Including Tremor Models) trucks with performance sound style and durability in mind. The muffler is specifically designed to give the 6.8L and 7.3L engines the classic S-Type sound without any drone. This system can be adapted to the different wheel bases offered by Ford. 140843BC comes with the front extension pipe for the Crew Cab with Short Bed (6' 9") 160" Wheelbase configuration. By removing the front extension pipe it will fit the Regular Cab with Long Bed (8') 142" Wheelbase. Add 60691 for Extended (Super) Cab with Short Bed (6' 9") 148" Wheelbase 60692 for Extended (Super) Cab with Long Bed (8') 164" Wheelbase or 60693 for Crew Cab with Long Bed (8') 176" Wheelbase vehicles. This system features a 5" round black chrome on T-304 stainless steel tip. Using BORLAÂ Stainless Steel Polish p# 21461 is NOT recommended with these black chrome tips. We suggest cleaning the tips with hot water and a microfiber cloth. A system with a bright chrome on T-304 stainless steel tip is also available. BORLAÂ Cat-Backâ„¢ & Axle-Back exhaust systems feature patented straight-through and multi-core technology to unleash hidden horsepower. Increased exhaust velocity adds power driving excitement fuel economy and the distinctive BORLAÂ Sound of Power respected by motoring enthusiasts everywhere. Each system is built from premium high-quality T-304 austenitic stainless steel superior to T-400 series knockoffs (such as 409) to give you the absolute best in performance and durability. Ultra-smooth mandrel bends ensure maximum flow & power and precision computer numerical control (CNC) manufacturing ensures an accurate fit. Best of all BORLAÂ stands behind every system with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.