Vehicle is a 1999 5.9 w/ 108,000 on it.
Also installed is a Viper Autostart/ Alarm

Here is the rundown. I'll try to be concise. I went out to the truck the other day and it wouldn't start, it didn't even crank. Dash lights, head lights, radio, etc. all work.
Initial thought was dead battery. Tried to jump it, nothing.
Checked Fuses (Good)
Load tested Battery (Good)
Time to test the starter. Removing it turned out to be more difficult then expected. Had to take out the bottom stud with the starter as it didn't want to budge. I ended up replacing the starter cuz I beat the other one up so bad trying to break it free. New (Napa Starter) Still nothing.

Read lots of post on this problem and "check for corrosion" "check battery connections" kept coming up. I replaced the positive wires to the starter and to the relay box, cleaned terminal posts, and checked grounds. Still Nothing.

Swapped Starter Relay with a known working one. Still Nothing
R&R: Neutral Park Switch, Crankshaft Position Sensor. Still Nothing.

I'm tired of swapping parts, chasing this problem. I might just be over my head and have to tuck my tail and bring it to the mechanic. I am going to bring it in anyways as it has a break in the exhaust. Putting on new headers & y-pipe and I'm not going to break any knuckles or bolts trying to break them loose. (but that topic is for another thread)
Any other advise would be appreciated. Thanks

 

OK, I was hoping to hear any advise. I'm gonna get it towed to the shop tomorrow and get it fixed. I will follow up and let everyone know what the problem was.

 

Please do. I got a buddy with the same issue and has the viper installed.

 

my first step would be to remove the alarm it could be as simple as the anti-theft immobilization being active, these trucks are notorious for aftermarket (installed after the truck leaves the assembly line) electronic systems (specifically alarms and remote starts) causing tons of problems

 

Got it back from the shop the other day. Turns out it was a short to the Neutral Park Switch. The replaced the wire and it runs great! Hope this helps out a little bit.