The Truck gets looser over a run you will need to make it tighter early in the run and if it gets tighter you might consider loosening it a little bit early in the run.
Set Starts off tight and gets looser as the run goes on. If it is too loose at the end of the run consider adding some more spring to the left rear. Other options would be ballast forward or trackbar down. The opposite will loosen it. I strongly suggest you put in a full fuel run before adjusting.
Overall Tight/Loose: Trackbar up will loosen and trackbar down will tighten. If possible move both sides equally. Cross Weight can be used as well but it is a complicated process
Entry Tight/Loose: Ballast forward will tighten the entry and Ballast back or negative will loosen entry.
Exit Tight/Loose: Rear spring split. a larger spring split will make it turn better on corner exit and a smaller spring split will tighten it on exit
Long Run Ballance: Ballast will have some effect on the long-run balance, back or negative will wear looser over a run and ballast forward or positive will wear tighter over a run. In general, if the car gets looser over a run you will need to make it tighter early in the run and if it gets tighter you might consider loosening it a little bit early in the run. There is a lot of give and take between short-run speed and long-run stability.