There's parts that interchange btw the two. Diff parts, flywheels, shock springs I think, clutches, probably spurs and bells.
I know they don't make the original gas truck any longer by ae, but thundertiger makes the exact same truck now that used to be the gt only now has a black chassis.

Even before being bought out they used thundertiger engines. They actually are nice engines. The small blocks on the gas trucks have excellent carbs, I'd say nearly as nice as the coveted os carbs. I ran a ae .28 this summer just to try it out. Once I sorted out my fuel tank problem the engine was excellent. It was a little difficult to dial the engine in, but once it was it ran like a vspec with less runtime.

But anyways.. There's so many good things out now under so many different names I wish I could just try one of everything. lol
Good luck with your mbx6, they sound like an excelent buggy.