i have a 1990 Z28, 305, 4-speed auto

when it is in gear, no matter what gear (except neutral and park) reving between 25-3500 RPM's there is a squeak coming from somewhere under the car..... i dont have a lift and its hard to lay under the car while its moving so i cant really find out where exactly its coming from.

just wondering if this could be a common problem (i have 155,000 miles on the car) im assuming it is a bearing somewhere...

 

I think this is way too vague to get much help. Only when the car is in gear? When you are moving? Stopping? Stopped? Bribe somebody to stick their head under there while you rev it

 

Have you checked the tension/condition of your belts?
Mine did it when the radio was running and it would only do it in gear. The alternator load plus the lack of proper tension caused it to only squeal in gear running in the same RPM range that you described.

 

i know its very vague.... its hard to figure out much more on my own... and it does it whether you are moving or stopped (in gear, standing on the brake and reving it)
I was also thinking it could be one of the tensioner pulleys, it sounds similar to how the pulley in my truck sounded before it grenaded, but my truck did it in gear or not....... but thanks, that gives me something else to check