This part fell out after I took out the last of the alternator bracket. It may have felling unnoticed before or been there all along. Does anyone know where it goes?

 

Appears to be some kind of arm. Any controls not working?

 

Looks also like some sort of shim. Try to find a place (if everything is not back together) where that tap at one end might seat.
If it is all back together, make sure everything is tight and snug. Start the car and make sure the belt is tracking correctly.

 

Ya the guy at NAPA said it was the alternator tracking shim but I can find no info on it or see whereit goes. It looks like it should be easy to find but is not

 

As a side note the holes are of two different sizes.

 

If a "tracking" shim assume would not be shown in a diagram as not stock from factory. Most shims are just thin washers that move alt one way or other to line up pulley with the others. But some are more complicated as shown in the link below:

http://www.summitracing.com/parts/rn...FYk-MgodjUMAqw

Look at alternator pulley to determine if it it aligns with other pulleys and if not in what direction is it off.

Assume for your shim to work, the alt bolt(s) would need to go through a bracket hole(s) to move both top and bottom portion of alt in or out. Is the slot in the bracket wide enough for one of the ears of the alt to slide into, or perhaps work with belt tension adjustment screw setup?

If you can't figure it out. Just check alt pulley alignment with other pulleys and use thin washers to adjust it as required. Typically you can find thin stainless washers at hardware stores.