UE uses ofna spider diffs in their TVS & Ultralite kits- you wont get much better than that really, but regular ofna buggy diffs or the HB lightning buggy diffs are near-as-dammit bullet proof regardless..

Can I use TRX CVDs with UE 6 spider diffs?

Maybe, but the output cups on the diffs are a little shallow, so the cvds may popout if you dont screw the pillow balls in. Most guys tend to change the output shafts/ cups to something longer/ deeper, or use the rc-m output shafts to fit deeper traxxas drive cups. Mike is out of shafts at the moment, but you can make your own using traxxas part #5454 & cut off the threaded part.

You could go with Revo drive cups. They fit and are just a little bit deeper.

Sparky

http://www3.towerhobbies.com/cgi-bin...?&I=LXTPP0&P=7

Oh, you mean those for extended rear wheel base arms?

Yup, those be the ones.