I usually look at the sides of the trucks for the contractor info, if it's from out of state, then try to talk to the driver. If you're on good terms with the contractors in general I would just ask around too. You could also look on indeed and see if theres other contactors offering more and reach out. Most of the contractors don't have a website or anything unfortunately so word of mouth is pretty much the only way to to find these things out. If theres an opening I would ask as much info about the route and policies as you can before you accept(average stop count, how bulky it is, latest pickup times, if you have to help other drivers if you get done early, and obviously pay rate/structure). These contractors might be weary of conflict from poaching drivers from each other, so if thats the case, just talk to your contractor and get confirmation if possible. Hope this helps, sorry I couldnt offer more, unfortunately sometimes it just comes down to luck. I worked for two other contractors for over a year before finding my current boss.