Sorry, my bad.
I was meaning on my engine they are far away from to be even close. Shaft lenght ( inside) height, width etc. realy far way, but in the mean time it took for me 5 minuts to drop on my son's MTX3. I don't say I did in purpose different dimentions, but during the design everything came up differently from existing designs.
So we spent some time to be able to fit in existing cars and save our calculations.