Box measures 147 inches from tailgate to dog house. Box 84 inches wide, but has 45 degree corners so only 63 inches of it is flat on the floor. Sides are 45 inches without the side boards on. The unit must be self contained, power for the work lights and amber lights may come from the truck trailer plug if they don't exceed the amperage of the standard trailer plug on an industry standard set up on a dump truck. Power for the spinner, conveyor and vibrators must come from the gas engine on the spreader unit itself. Controls as stated in description must control spinner and conveyor from cab, must be able to turn of and on as well as turn vibrator off and on from in cab. If not wireless controls must be wiring that is easy to put in cab and remove seasonally by operator. Required included stand should be permanently attached to spreader and easily fold or drop out for unloading. Operator should be able to remove spreader by self without needing a forklift by just using the dump bed. Extending buy for those that needed clarification.