What would cause a screeching noise that only happens when accelerating?

What is your question?

My car was recently in the shop to have the transmission replaced after coolant leaked into the transmission from the radiator. I can't remember if it made this noise before the transmission blew up on the freeway but the transmission shop told me about it when they brought it back. The car sat inactive for about 6 weeks and I replaced the radiator myself to save costs. I just got it back a couple days ago and the screeching noise is really loud when I accelerate. It sounds like its coming from one of the pulleys on the serpentine belt.