Not at all just pay attention where the bolts go...
I remember something about that...I always thought it was steel and delrin not alloy...They use to recomend using the Delrin gear with the steel metal slipper gear In the old days but it looks the other way around now and they now come standard.
i use to have a old black chassis rustler with a slipper. And the first part to brake after a brushless conversion was the idler gear... Then the diff out put yokes
if ur going to rebuild the gearbox have u thought about replacing the gearbox housing with a RPM housing?
and once u have a good gearbox, the next thing to look at is the axles or yokes.