I know this is old, but it might help someone. The Jacknife (there is one K in the name) I don't know much about, just seen em on ebay, it's the 6v car with the "transforming wing" or whatever. Like you guys said, probably a lot like the Hi-Jacker. The Jackknife (there are 2 Ks in the name) was a semi truck with a detachable trailer that was powered by the TMH battery.