The S-25 would fit I think, as the engine plate has multiple engine mounting positions. You'll probaly need the S-25 engine mounts though, which most likely would fit in the slots on the engine plate (rather than the holes). It would put the drivetrain under strain, but I reckon it would hold up enough to use it. That much torque though would be uncontrollable in ANY stadium truck, the 2wd would just wheelspin and donut! I've heard of a lot people seem to have trouble contolling the power with the O.S .18s...

For the aluminium upgrades, GPM do a few parts, Fastrax do a range, and there are a few titanium parts from F4i. Not sure where to get them from the US though.