Should be a switch on the dash. If one tank is dry, the other will provide fuel. If it is a definite fuel problem, and neither tank supplies fuel when switched on the dash, I would suspect the switch, power to the switch and / or the tank selector valve. A bad selector valve could also not provide the proper power to the proper pump. Along the way could be relays, fusible links, etc. Start at one end and work towards the other.
Short version: your truck won't care if one tank is dry.
