Are O-Rings Needed in CVDs and UJs?

With default dog-bones, like the ones included in rere (re-release) ORV chassis R/C vehicles like the Frog, Brat,  Super Beetle, Blackfoot, etc., you need to use the included o-rings for them to fit right. But when you hop-up these drives with the MIP Super Ball Diff and Tamiya UJs (Universal Joints) or the superior Xtra Speed CVDs (Constant Velocity Driveshafts) do you need to use these little black donuts? Why or why not? We take a deep dive into this on this episode of the RC Deep Dive.