Project 6 Seater Hilux Buying a used steel dual cab tray - Repairing upgrading & what to look for

For the buyer of the new or used cab chassis utility, purchasing a used steel or aluminium tray can literally save you thousands.
For our project 6 seater Hilux, we have purchased a used steel Hilux tray for $1000 and are making a few upgrades before we fit it.
Here are some things to look for if you are buying a used steel tray - the good, the bad and the ugly.