[nitrostarter]

4s, a 1900kv buggy motor, and badlands you could probably go with RPM bulls and keep the stock diffs and save the weight. That slipperential should help preserve the diffs as well.

The newer maxx and Summit style driveshafts are thicker and have better joints than the old school Maxx driveshafts. They do hold up to the power better so you could like get away with these without issue. A set of Traxxas CVDs would pretty much solidify the driveshafts and add 0 to little weight tho.
Centers should be fine with stocks.