You're nuts for driving it for a while knowing that those cylinders where out. You should have diagnosed the problem then and gotten it figured out. It would have been a lot easier since you already pin pointed which cylinders weren't firing.
As far as it being dead and what it may be, what makes you think that it's the spyder? Just a wild guess out of nowhere? You need to actually diagnose the problem and find out what it is before throwing a bunch of parts at it. Does the engine turn over?
Remember about all 4 stroke engines. Suck Squeeze Bang and Blow! If your engine doesn't run it's either it's not getting air/fuel, it's not getting compression, it's not getting spark, or exhaust is not getting out.
The engine not running may be something like a clog in a fuel line or even a dead fuel pump. Try pouring a little bit of gas into the throttle body and turning it over and see if it starts up. If it does, take your bed off and pull the hose off of the out line on the fuel pump and turn the truck over, if it pumps fuel out then there is a clog in your fuel lines. If it doesn't then the pump is bad.
If it doesn't fire up by pouring fuel into the TB then it's time to check spark. Make sure all your plugs are sparking. If they aren't, check the wires, check the distributor, and make sure you have a good set of ACDelco plugs that are gapped right.
Next it's time to check compression. Get a compression checker. start pulling plugs and checking the compression and make sure it's adequate.
Engines are a lot more simple if you think of it in the 4 strokes. The easiest one for me to remember is like I said earlier. Suck, Squeeze, Bang, and Blow.
