EXCEPT Vehicles With Dual Rear Wheels. Extension pipe 60691 is used to adapt select Borla® Cat-Back™ systems to trucks with an Extended Cab with Short Bed (6' 9") 148" Wheelbase. 3.5" ID Inlet, 3.5" OD Outlet, 8.5" Long. Includes 1) 3.5" clamp. Built from premium T-304 stainless steel, superior to T-400 series knockoffs (such as 409), to give you the absolute best in performance and durability. Precision computer numerical control (CNC) manufacturing ensures an accurate fit. Best of all, BORLA® stands behind every extension pipe with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.