Only thing I can think of is brakes, the LF pads might be not be retracting enough in the caliper. But if that was the case when you hit the brake pedal the truck would veer probably to the left after letting off the brakes. Or the brake hose on the RF side is very restricted. Maybe it got pinched, but more likely that it is swollen on the inside and doesn't let fluid/pressure, equal pressure, go to both front wheels. I know you guys are thinking I'm nuts but a very long time ago I worked on Porsche cars, and my boss would tell me that could happen. Thought he was on drugs but one day a car came in with this type of issue.
How he proved it to me was hit the brakes with the wheels up in the air, depress the brake pedal as hard as you normally would. Then go to the wheels and spin them. In this case one wheel on this car didn't spin as easy as the other side. Loosened the caliper bleeder valve for that wheel and that relieved the pressure from the blockage in the hose to the caliper and the wheel spun freely.
So two possible issues.