So, I went to leave for work and my truck turned over a little and then did no more. I thought "huh, dead battery" and put it on the charger. No result. Then I tried jumping it with my landlord's van. Also no result. The battery showed 12.5 V and 13.6 V when connected to the running van. I put the truck on the charger and took the already running van to work. When I got home I tried to start it and no result. I'm pretty sure it's not the battery at this point, which means it could be the clutch interlock switch, the solenoid, or the starter itself. I'm pretty sure it's the starter, but how do I rule out the other two before I drop the money on a new (rebuilt) one?