I know more than I want to about trucks. I used to drive for a couple of different companies. The two speed rear ended trucks are really easy to drive. The 9 speeds and up are a little more difficult.
With the two speed rear ends you can drive it pretty much like a four or five speed when the truck is empty. If they are loaded you need to use the rear end to split the torque band so that it is easier to pull. So you put it in the drive gear with the splitter down. You accelerate up to around 1900 RPM in a diesel, push in the clutch and split the gear. !900 Rpm Clutch, push splitter down and shift. If push the splitter down after you shift, it is more likely to grind the gears. You can do it this way all the way up throught the power band.
On the bigger transmissions most truck drivers use the clutch for two things. One is to get started and the other is to stop. Any other time when they are shifting the are "slip shifting" or "floating the gears". In fact, after you get experience with the bigger trucks, you can tell if someone hs been using the clutch to shift with because it just doesn't feel right.
Let me know if this helps, if it doesn't tell me what sounds stupid so that I can change the way that I said it.
Scott