use hot bodies brake outdrive cups- way stronger I had to machine them down a near the base, seemed to bind a little when the top plate was tightened down

You can get a whole center diff complete for $20 off ebay from a HB D8T- also the HB D8t 101 mm drive shaft assembly work also in the rear, much lighter. I use them on the front also with the Xray xtra long outdrive cups.

If anyone gives a crap I have been running vspec .21 with a HB D8T 13 clutch and 50T spur- Even with the extra weight of this truck it is an excellent combo for racing