Look at the end of the class write up. If the engine class is not listed there is no class available. There was a J class Mod Sports that ran at Speedweek, no J engine class and the body could not be changed back to stock so it was a complete waste of resources and time/effort.
DW
Thanks for the info, I was a little curious about engine c.i. limitations in the mini truck and the production supercharged class.