ok i found this one and this is the one you will want if your going to use a bump/starter box. i know its an axial back plate but it also fits your engine. its still the original engine that came with hellfire, right?
http://www.amainhobbies.com/product_...late-28-non-RR

when you take off the rotostart and all of the gears and all then put this in the place. make sure the piston in at the top of the stroke (closest to the glow plug) and when you put this back plate on the will be these indentions and like a cut you and you want that to face up so when the piston comes down it wont hit the plate. always remember to have the piston at the top of the stroke at anytime that you take the back plate off or putting it on or you will break your piston. that has happened to a ton of people.

i hope this helps you. and once you put this back plate on it should be a little faster off the bottom end and you might gain some more on top also, its not a huge difference but ever little bit counts IMO. you have a good truggy by the way. i almost got one back when i first started but went with a buggy instead.<br type="_moz" />