bigwick, I would start with disconnecting the battery again (prevent draining it) and then pulling the big wire off of the back of the alternator and taping it up. Also, pull the wire running from the starter solenoid to the starter too. Now, reconnect the battery, do you still get a large spark (may get a small arc as things charge up, but it will be barely noticeable)? If yes, then your problem lies in the truck itself, let me know and we will get you taken care of.
Now, since the terminals are not sparking when you connect up the battery, we know the problem lies in 1 of 2 areas. What you will want to do first is to get yourself a pair of gloves and then touch the starter wire to the starter solenoid (where it should be mounted). Did you see a large arc there? If yes, then your starter solenoid is toast and you need to fix that (failed internally, hence the click, but the draining of the battery). If no, then odds are your problem is in the alternator, you need to replace your alternator.
I would also do a once over of the wiring between the starter solenoid and the alternator if you suspect the alternator just to make sure that you are not replace a good part. Please keep in mind that this is all assuming you don't have something aftermarket in the truck like an amplifier and whatnot. Past experience has shown that most of the time, it is the aftermarket stuff that causes problems like this. If you do have something aftermarket, pull the fuses/disconnect it as close to the battery as possible to eliminate them too. Reconnect them after reconnecting the starter and use the same philosophy of "touch the wire to the post, check for sparks" and do one thing at a time. Still leave the alternator for last.
You da man!
