Wow... they didn't put a slipper in that thing! Not a lot you can do except to never land when your on power.
The QUANTUM✚ has a center diff... might want to see if you can fit that in it instead of just the solid spur. Typically I've seen brushelss trucks either with a slipper setup or a center diff, but I've never seen one that didn't have either. Having nothing in the center to absorb shock is stupid this day in age. Would be different it was a slow brushed unit, but it's not.
Doesn't look like you can, they are built completely different.