There isnt too much you need to upgrade then really- common weak points are:
For bulks, you could go the FLM or GH route for regular aluminium items.
For towers, I'd Go FLM or UE knuckleheads.
For A-arms, RPM items are probably best ( maybe true-track rears )
For diffs, you hav3 3 options:
LST2 diff mod
FLM Hybrids ( in which case you wont need regular bulks )
For the Chassis, there are a couple options still:
FLM 3905 chassis
Xtreme Racing CF 3905 chassis
If you prefer aluminium + low CoG, then consider doing a little work like this:
Overall though it isnt a huge amount of work or money that needs to be expended on the truck to make it something really special..