The spiral-cut Lightning gears don't fit in the Hybrid bulkheads. Gotta use the bevel cut ones.

Your best bet might be to check eBay for a Hyper 7/8 diff pair, or original HB Lightning diffs. The Lightning Stadium has spiral gears.

The Ofna Spider diff is a torsen diff. I think the Maxx would blow that up. :P

Edit:

You could also build up a LST2 diff using the Hot Racing Aluminum Cup w/ Steel Outdrive Plate.

http://www.ebay.com/itm/Losi-LST-LST...item53f89658b5

I don't know if there's any way to make a stronger diff at that point. Yikes.