Losi Smart Diff and plastic spur compatibility
 

Does the Losi Smart Diff and the losi plastic spur conversion work together?

It should the SD works fine with the Kyosho plastic spur.

does the kyosho fit without dremeling? Is it a better choice than the Losi gear?

It's a tight fit, but snaps into place as you tighten down the screws. From what I've read the Kyo spur is more durable than the Losi. If you do go with the Kyo spur then also pic up the Kyo outdrive o-rings.