The clicking in the cab and the EEC relay was from me not realizing I had the hazards on.
After prodding the engine with an ohmmeter, I finally figured something was off; I wasn't getting a circuit through the engine block and ground on the battery. Although, I thought I was sure I was grounded because I prodded the starter with the ohmmeter... but, who knows because I've done a lot of testing and didn't take notes.
So, the culprit? The stupid strap that grounds the battery to the chassis. The connection on the truck body was corroded. After I cleaned and sanded that a bit, the truck fired right up. It only took me close to five hours to find it
. At least I learned a lot about the electrical system in the process.
Thanks psychopete and ranger302 for the time you took to help me out--I truly appreciate it.