They were all 318s. They had planned to make a 360 version for 1990 but it never happened. The Shelby 318s did have 10 more hp due to the dual snorkle intake, exhaust manifolds, and computer. (Not sure the exhaust made a hp difference but they were specific to the Shelby trucks, and replacements listed for nearly $1000 each according to my old crash books. :protest: )
You could buy a '30 hp upgrade kit' which consisted of a 360 throttle body, a different computer, and a different muffler, but it was kind of pricy IIRC.
Dallas
