I didn't recommend that you go for the one without the 'special machined crank'. I simply said I think the standard version would be fine for you. If you want, go for the modded one...

They might make a two speed for the Hellfire (or at least may do in the future), but that would eliminate the center diff which is quite important. These engines have so much torque, a 2 speed is not necessary anyway. Better to keep the center diff.