1979-93 Ford Mustang Foxbody, Headers with 2" diameter primaries and 3.5" OD (outside diameter) merge collectors for 9.5" tall deck aftermarket heads. Designed for use with cylinder heads that have a 2-o'clock, 8-o'clock bolt pattern.? Set up to work with TH400 auto transmission, and works with either UPR or AJE K-members / trans-crossmembers. Headers fit the following heads for the 9.5" tall deck: Brodix T1 F STD X, SVO 351 "N", Trick Flow Twisted Wedge, Victor II. This header kit comes with high flow cats.