You don't say what year your truck is, but if you have drum brakes on the rear, make sure the REAR brakes are adjusted properly. The so-called automatic adjusters are NOT reliable. If the rear brakes are out of adjustment that can cause a bad pulling condition.
When the front brakes are serviced make sure the pins are polished and lubed with silicon brake grease like NAPA sells. It's in a can and is a nasty black color. Also smooth the slides on the caliper mounts and grease them. Make sure that both calipers slide freely.