Probably all. Shorty headers are a serious PITA to install so making sure you have a set that is direct fit will minimize blood, sweat and tears. I was fortunate to have a wrench that has his own shop and after the first install that didn't work, we compared the second set of headers to the Gibsons and could see that the second JBA would not fit either, so we sent them back. We were also fortunate that the sales guy at Summit Racing was kind enough to look at photos of the OEM exhaust manifolds and compare them with different sets of headers and came up with the third set, also JBA, for the '05-'08 F-150. If you are going to install a set of shorty headers, suggest that you pick the easiest side to work with and if that side doesn't fit up, send them back and try another.