hemi 4 speed
Sounds like ya'll have pretty much figured it out. Had one of these beasts in '73 (SS Dart Hemi) and the transmission did not have straight cut gears. It was a real bear to drive normally because you had to hold it in gear or it popped into neutral when you let off the gas. Floor it and bang gears though and everything worked as slick as snot on a window. Truly scary car.