A spreader assembly for spreading a material and for mounting in a bed of a truck is disclosed. The assembly includes a hopper and a frame for supporting the hopper in the bed of the truck. The hopper has a length extending between a front end and a rear end sized for placing in the bed of the truck to hold material for spreading and has an outlet spout with an opening for discharging material therefrom. The hopper and the frame are each formed from a thermoplastic material.