Your welcome, I was unaware that you were able to turn it over by hand, which is good because the intake maifold gasket replacement is not fun. on a side note, I pulled my plugs and tried turning the motor on my blazer over and she started cranking after it spit out a ton of fuel from the #3 cylinder....which then caught fire and engulfed my engine bay in flames. I think I got it out with the garden hose before it did any major damage. Good luck with your issue I look forward to finding out what the solution will be.

 

Hey, so, I couldn't do much with it last week, but there are new updates today:
I took out the battery, the starter motor and the alternator and carted them to the local auto parts store (in this case O'Reilley) They evidently test electronic parts of the car for free.
It turns out the starter motor is OK, the battery was just empty, but the alternator was locked up/jammed/seized (I noticed it was hard to turn, but didn't know it was supposed to turn smooth as glass).

So, it seems the alternator is at fault.
Keeping my fingers crossed that this $90 investment was worth it, I'll be putting it all back together later this afternoon.

 

OK - I put it all back together with the new alternator, and it started right up..
YAY!!!

Thanks again for all your help.

Analyzing the problem and the solution, this is what seems to have happened to my car:

The alternator locked up in the middle of the road, and evidently put enough force on the engine via the fan belt to halt/slow down enough so it shut off and made the transmission pop into neutral.
The locked up alternator must then also have prevented the starter motor from turning the shaft/cranking.

When I turned the motor over myself, I had the fan belt actually removed, so it makes sense I could do it manually.
I didn't know the fan belt had enough traction/strength to effectively block the motor like that.

With the new alternator, the car actually seems to drive smoother than it did before. I think it sounds more healthy. Maybe there were bearings in the alternator that already were on their way out and made noise.
As a secondary problem, there might have been a low battery charge involved as well (the alternator might have been damaged already and not doing its job so well, but I never noticed any problems up to that point). But the battery still had enough charge to operate the starter motor directly when I tested it disconnected from the engine.

I'd be curious of course if you had more thoughts about it, but I'm just really happy it runs again... for a moment in the process I had been almost certain the engine itself had died.

Cheers L2000