The stocks may last a bit, but like CHC said, they wont last forever. Even a aluminum cup properly shimmed with aluminum diff cases should last atleast a year or so. A perfectly shimmed stock diff will last longer than a unproperly shimmed aluminum diffs.
The problem with nitro's these days are that they arent brushless... LOL
Losi 8ight e
MMM / Neu 1512 2.5d/f
Thunderpower 5s 5000