Dump box beams have slight sag

The 81 Kenworth dump I just purchased has an aluminum dump box. In poking around at areas I likely should have paid more attention to prior to purchase(there should be an acronym for this) I discover the beams under the dump box have an ever so slight sag. Results in the beams not bottoming out at front until a bit of load placed on box. (at this time im talking excavator bucket bearing down . Ive yet to haul a load of anything profitable.)The overall sag in the aluminum beams under the dump...

Dump box beams have slight sag

Dump box beams have slight sag