I wanted the pillow ball setup in the rear, but didn't want to spend an arm and a leg for it. So Ebay to the resque and bought OFNA Rear Pivot Ball Kit, MP-6 Part# 31297 for 14 bucks plus shipping. I had to shimmy it a bit, but now I have a nice 13" wheelbase. The thing is on rails and zooms like mad.
Here's the bigger motor. It's scary to drive with this beast.