Here is the Hayes HDX off-highway logging truck. The truck has options for multiple colour configs, front wheels, lights, and some other options. The trailer loads on the truck while empty and has a loading strap for lifting. The truck and trailer both have tripping bunks for dumping an entire load at once.
SimpleIC is required for the trip bunks to work. There is a trigger on either side of the bunk for the stake on the opposite side. I would suggest using a machine to push the logs off and building a small ramp for them to roll down. Enjoy!
Thanks to Mayto for the 12v71 sounds.