Treated ship lap yellow pine in 2x6 dimension is an ideal lumber for useas a truck body floor. I've used it in 90% of the bodies I've built and or sold over the last 40+ years in the business. Far too many of them to count and they hold up fine if properly installed and cared for.
In another thread it was asked if KampCo is a good supplier. Of course they are or I would not have originally recommended them. Lots of personal experience with the owner. Most of the rails are made for 1.5" dimension material so forget about using 2" mill run oak. Typically they do not sell to individuals so don't expect wholesale prices.
