Crankshaft pulley/Harmonic Balancer and damper

It sounds like you have two different problems but lets start with the bolt. Remove it and look at the threads. If they're chewed off the bolt, head to any salvage yard for a replacement. If the threads in the hole of the crankshaft are stripped out you can avoid a REAL expensive repair by installing a Heli-Coil insert. The hole is drilled with the supplied drill bit, tapped with the supplied tap, then the insert is threaded in to form new threads.

If the center hub of the damper is spinning but not the outer ring, the two pieces are delaminated and it will have to be replaced. Auto parts stores have huge catalogs filled with nothing but replacement dampers.

If just the bolt is spinning but not the center hub of the damper, remove the damper to inspect the key. A loose bolt will let the damper slide off and wobble out the keyway slot or damage the key.

I suspect you're seeing the part with the white arrow is spinning. That is just a giant washer under the bolt head, not the center hub. It appears the center hub is shown with the green arrow and the rubber bonding material is between that and the outer pulley with the red arrow, but it's hard to tell for sure.

The closest thing I could find for a replacement is in the lower picture from Rock Auto. That is for a 3.4L. The rubber is between the blue and purple arrows.

My guess is since the center bolt was loose, the key that went in the slot with the yellow arrow is missing or ground away. That will let the balancer spin on the snout of the crankshaft.

You're gonna have to pull it apart to examine the pieces. Specifically, look at how nice and smooth the hub is in the lower picture up above. The slot has nice sharp edges. There's going to be a similar slot on the snout of the crankshaft.

This same problem happened to me a few years ago on my daily driver '88 Grand Caravan. I was just leaving the scrap metal recycling place and pulling a big trailer when I suddenly lost power steering. Then I noticed the charging system wasn't working either. There was no noise associated with the failures so I assumed the serpentine belt had broken. (It's only the second one since the van was new). Instead, upon looking at it, the entire harmonic balancer was sitting at an angle and not turning. Drove it ten miles to home like that because that belt doesn't drive the water pump.

When I took it apart, the bolt had fallen out and was laying inside the plastic splash shield, and one side of the center hole, (by the yellow arrow), was ground down about a half inch. The woodruff key was gone, but surprisingly there was no noticeable damage to the crankshaft snout. I did leak some oil out because the front main seal seals against the outer side of that hub.

Cost me five bucks at the local salvage yard for a used balancer, bolt, washer, woodruff key, and the stamped steel plate that keeps the timing belt centered on the sprocket. The engine just turned over 396,000 miles an hour and a half ago.

Crankshafts are hardened in certain areas, but I suspect the harmonic balancer hubs are not because they don't need to be. For that reason I think you're going to find that your crankshaft snout also will have little or no damage. If I'm right, head to the salvage yard like I did. You might pay a little more than five bucks though. I ran out to the van and pulled the parts off myself. If you're lucky, they will have a core engine that is going to be scrapped that they can pull the parts from so they don't have to ruin a good engine. If you pull the parts yourself, do not pry against the outer ring / pulley, at least not very hard. Too much pressure will tear that rubber insert that bonds the ring to the hub.