Hello. I own a 02 z-28. during acceleration about 2k-3k rpms it seems that the car squeels, after a certain point, it stops. During revs ive been asked if I had a blower? I went through all the pulleys grease packed the bearings with mobile 1 high performance bearing grease and it seems that when i spin the altenator pulley by hand, it makes a squeeking sound, everything else spins quietly. I do have a cracked flexplate so maybe the *****d up part of it is whistling when spinning. I don't know. Has anyone heard of this happening? Oh I also changed out the main belt.

 

You shouldn't be running the car at all with a cracked flexplate. If a piece comes off and throws your crank out of balance, bye bye main bearings

 

GM alternators have been having bearings do this for decades. Most just get a new/rebuilt alternator. But just the bearings can be changed.