Have several older boxes that I have acquired over the years. Nothing fancy but very usable. Could use a coat of paint. I don't have keys to any of them but you could put new locks on them. All of them would be great for a farm truck.
Crossover is extra wide and has a big metal sliding tray in it. Also has tool rack on back that is bolted to it. $40
Green top side boxes are aprox. 6' long. $50 each
White side boxes are 8' long. $50 each