Gidday Neil,
from a brand new truck, the only thing really needed is the aluminium spur gear carrier as the plastic one melts if you have the rear brakes working very hard.
A few of other options allowed for durability are a roll over bar/carry handle, a rear bumper plate, side intrusion bars, brace between the front A& B pillars and the alloy front hubs.
I have only just changed to alloy front hubs as I found at the VICs, my lower pivot ball screw came out in the final.
It seemed that as I had to screw it through the plastic hub before it reaches the steel insert, all the thread lock was wiped from the screw. It wont happen with the alloy hub.
Eden