And yes, excess should go back to the tank--not to the suction line. Its an advantage if you can start the pump without climbing onto the bed of the truck. Handy if you can add water to the tank without climbing to the top of the tank. Be sure you can change the oil easily--and fill the gas tank. Take a look and be sure you can change the pump diaphragms easily--I hear in some cases--you must unbolt the motor(swing it out) to reach the diaphragms behind the D-403.
Good agitation is helpful--necessary if you use powders. Try to be sure you can reach the agitation valve without getting into the bed.
A "roof" over the motor helps keep it dry and prevents chemicals from dripping off the hose and into the engine--damage can result.
Referring to your above fresh comments: Three or four agitation nozzles inside the tank should provide enough agitation. Be sure the filter is conveniently located so you can clean it easily.
If you spray fertilizer--plan on rust and repainting every winter.
Last edited by RigglePLC; 05-28-2013 at 10:14 PM.