I was still surprised that the cen back plate worked on the hpi engine. I did it she kicks and grins to see if it was close and (WAALLLA) it fit. maybe the engines are subbed out. The bushings are the same size in the back plate and the screw holes line up perfect. The shape of the backplates are the same just different screw holes for the hpi pullstart. . i wonder if some one like Enaya or another Taiwan CO. is making engines for them under there specs.