You can probably just use a set of Ford manifold gaskets, but if you buy a new set of long tubes they should come with gaskets I would think. At least you don't have the problem Automatic guys have with long tubes, they don't make many brands that will fit on automatic cars, and I think they are a lot more expensive. I think I will just stay with my stock cast iron manifolds, if I was going to do headers at all I would go with SS FMS shorties. A lot of trouble to install long tubes or any headers, and as I said long tubes for autos are scare, and high.
Rick Kilpatrick, AAS Automotive Systems Tech, Alamance Community College, Class of 99. 06 5 speed manual Mustang with Pony pkg : GT Mac Mufflers, true duals with one custom pipe. 2.5" system. GT bumper cover, all installed March 7&8 2006. AFE Stage 1 CAI, Motoblue Underdrive pulley, GT aluminum shifter knob, honeycomb rear blackout panel,and dash kit installed. Roush hood scoop and side window louvers installed. SS taillight trim has been installed, new alum. GT steering wheel installed.