What the PUCK

[Sentinel]

Ok weird thing, started the car(3100) 2 days ago, was running great(minus the alternator, don't ask) didn't drive anywhere, then yesterday, started it up again to a god awful grinding sound coming from my serpitine belt assembly, finally tracked it down, on my config there are essentially 2 crankshaft pulley's, 1 closest to engine , drives sepentine, water pump ect and second was mounted to drive new alternator mounting position. Now the second one always sat  real close to this Metal/Rubber puck like thingy(Damper Assembly I think it's called) which is mounted into the cradle, for some reason they got too close and the crankshaft pulley is rubbing on the metal surface of it, causing the grinding noise. My question is, what is the purpose of this little bugger.  

[2ML67]

Lets see if I understand this, you played with the alternator bracket unbolting it with the weight on the engine. This is bad as the bolts also go through the front engine mount, thus stripping bolt hole. Now you are running engine without this bracket in place which worked with the front mount. Sounds like the front mount is loose or has been moved and the pulley is now rubbing on the drive line dampener which is there to keep parts from hitting the frame. To remove the front mount or any mount the weight of the engine needs to be removed from mounts. In these cars just like front wheel drive cars all the mounts are designed to work together removing one even for a short period of time without bracing weakens and damages the rest of the mounts.
If you would like I can stop on the way to the meeting and take a look for you.