Wrecked truck need help

[NicoSlam]

So my brother was hit while at a stop sign on his 72 GMC sierra classic around two weeks ago. purchase receipts plus some other improvement receipts were provided to the Insurance company as they requested but they came back and offerd $2100 + truck. They considered the truck totaled but what can we do as i feel you cant find a truck like this for $2100? Has anyone gone thru this and what is the best approach? My brother is not trying to become rich but simply get enough cash to replace the truck. Oh. and $2900 and they keep the truck.