What model of Emaxx do you have exactly? There were 2 versions of brushed Emaxx, the black chassis 3906 and the newer grey chassis 3905. The 3905 has a basically bulletproof transmission and different knuckles which take different axles. Btw the plastic axles and center driveshafts aren't called cvd's. Technically they are universals but people generally refer to them as plastic sliders.

MIP makes what is probably the strongest cvd's for both versions of the Maxx. Traxxas has their own line of cvd's for the newer Maxx which I ran for awhile and had no issues with.

I recommend going through your diffs to make sure they aren't worn out and to properly shim them. Play between the ring gear and pinion can cause failure of either or both. The best thing to do is get rid of the Teflon washer on the pinion as it will wear and crush changing the mesh. Replace it with metal shims, I believe the size is 8x6x.2mm that you want. Assemble the diff in the outer case with axles or cvd cups on the outputs and the pinion. Pull out on the pinion and rotate the pinion back and forth while holding the outputs to check for play in the pinion. Add shims to adjust pinion depth until there is no play around the entire ring gear and the assembly spins smoothly. With that set try pushing the pinion in, if the pinion can be moved in and out place shims behind the drive cup on the pinion until it can't be moved in and out. Don't put too many as it can cause binding. It's time consuming but your diffs are now as strong as they can be.

Chassis wise I feel the Maxx really needs aluminum bulkheads, RPM arms and either RPM or aluminum skid plates. These can be replaced as you break stuff because t all depends on how hard you drive. After upgrading to aluminum bulks I recommend upgrading the hinge pins as bent pins are a pain to remove from aluminum bulks. FLM seem to be the strongest premade, I've bent Lunsford titanium fairly easily. The strongest are made from ejector pins that you cut down yourself. Google Tmaxx ejector pins if interested in this at all.