These diffs didn't have spider gears. The ring gear(86031) has about eight holes around the center for the ball bearings, then a metal shim on each side of the diff ring gear and the and the ring gear is mounted between the two piece shaft. Kinda like a slipper clutch.
Right now, I am using just the metal input shaft and using the plastic diff. I will see how the spider gears and such hold up with my SH12. At least the input shaft won't strip anymore.
Speaking of diffs, I did notice the other tremor(which was a redcat) has some problems with the joint cup gears(86023) meshing with the diff gear. It's looks like they were replaced at some time because they are completely white in color and new looking and the rest of the diff is almond color. If they were replaced, they are defective parts. Which I blame the manufacture, not you. I can see why you got out of the 1/16 scale nitros. But I have no complaints though. There's always a way around the problems. It looks like the pin hole in the center of the joint cup gears are not deep enough to allow them to mesh a little more with the spider gears. Because the spider gears move up, down and all around because the lack of mesh. I will look into finding a cure for that....
Here's a pic of just the ring gear from Redcat's website: