Slant six in a Miata ? Why ???

I think it’s kinda cool. But I really want info on that 4wd looking 4 door Valiant in the back ground!!
He'll get back on it. He jumps around alot. I think he's entering it in a race or something. There's a date he has planned for it to run. What little I know is, its the valiant shell on a 70 Ish Dodge truck frame that was sectioned, and he fabbed the floor. That's about all he's done with it.