I apologize now if I do something wrong as I am new here, but lets get to it...

So probably around 2 months ago now I was coming home from a friends house at about 8:30ish PM in the good old Indiana cold and after about 5 minutes my truck shuts off. No noise. Nothing. And yes I wasn't quite up to temp and I had changed my oil and filter approx. 700 miles before with Pennzoil 10w30 I believe. And it would not want to start back up even with a jump. My initial thought was something in the electrical problem so I replaced the alternator, starter, and made sure I had a good battery, and checked to make sure my oil didn't magically disappear. Still nothing. Later determined it is in fact locked up. It won't even turn manually.

I was wondering if anyone has any suggestions as to what it could be.

 

kinda sounds like what happend to my 99. Was driving along and the damn thing just died. Later found when I was pulling the motor the cam syncro sheared apart.

 

Did you notice oil pressure drop to 0 before the engine died?

Yes, as above mentioned the Cam Synchronizer on the 3.0l is a common issue but usually will have a high pitched squealing noise(similar to slipping fan belt sound) weeks before it fails.
Cam Synchronizer is in the old distributor hole, and like the old distributor did, it powers the oil pump, so when the Cam Synchronizer fails oil pump stops working.

Could even be a bad oil filter or oil pump failure that caused oil pressure to drop.

Oil cools the bearings and if oil flows stops the bearings over heat within a few seconds, this causes them to soften and "weld" themselves to the crank, engine RPMs start dropping and then stop, since the bearings are now softened and "welded" to the crank it will no longer turn, with starter or manually.

You should have heard a "ticking" noise from the lifters/rockers in the seconds before motor died, lack of oil pressure would cause that.

If no oil light or 0 pressure on gauge, and no "ticking" was heard then you could have a spun main bearing, just from failure of that one bearing or clogged oil passage on that bearing.

I assume truck will roll in neutral, so transmission isn't the issue?
Manual or automatic?

I also assume you have removed all the spark plugs and looked at each, and none show signs of damage, and engine/crank still won't turn with no spark plugs in place.

There is really no way to test for melted or spun bearings, engine must be removed and oil pan removed, then remove each bearing cap, main and rod caps, and see which one failed.

 

I didn't notice any warning lights or gauges drop nor the ticking that you're describing. And yes it's an automatic so when it's in neutral, it will roll (which is a good thing I suppose)

So hypothetically speaking if it was the main bearing i'd imagine it'd be loud and it wasn't. I didn't hear anything.

I hope to start pulling the motor within the next week if I can find the time and will keep you guys updated. Thanks for the suggestions Ron and Chris

 

A spun main bearing can make a low thumping noise but doesn't always.
Rod bearings are the ones that knock fairly loud.

After you get the fan belt off, spark plugs out and the torque converter unbolted try manually turning the crank again.