This truck can be filled using the standard fertilizer trigger, you can unload in to any spreader, works with the soil mod also.
The auger is raised and lowered with the left mouse button, the tarp is controled with N, and the lift axles are key V.

Credits:

The truck is from Bcbuehler the box is an edit of um moddings 2013 tender trailer
the wet kit tank if from Smarty of 18wos the Hydraulic levers were made by Oldiron
The ad strips were created by Chris George and the final scripting and assembly was done by ccc.