Chirping Rear Suspension

Hi Everyone,

I'm hoping that someone can help me or provide me some insight. Because I'm fairly new I can't post much but I'm hoping someone reaches out.

I purchased a 2005 Prius a couple of months ago, absolutely love the car, to say it's good on gas is an understatement, it's a smooth, quiet ride, the engine is smooth, really nothing bad to say in that regard.

After about a week of purchasing the vehicle I had my son and his friend in the back of the car and the car started making what can best be described as a chirping sound, I have a recording of it, but again, since I'm new I can't post it.

I took the car in to the mechanic, he looked at my shocks and realized that both springs were broken, so I replaced both shocks only to have the noise continue again. The shocks he's using are made by UNITY, not sure if they're any good, I've left the car with the mechanic as he's checked it and can't seem to find the issue, at this moment I have the car as the shop is ordering a new rear quick strut in order to replace the one making the noise, the noise appears to be coming from the driver's side rear.

I took it to another shop in order to get another opinion on it, they played around with the strut and used a pry bar which has improved the situation but not resolved it. I'm wondering if anyone else has heard about something like this. The noise seems to come directly from the rear driver's side quickstrut. The mechanic that installed the quickstrut is convinced that the strut is not the problem, he's been honest with me always I have no reason to think he's taking me for a ride but if not that then what? When he removed the strut he checked the body and there doesn't seem to be anything broken, cracked or rotting, so the body itself is in good shape. If anyone feels they can help me out I would greatly appreciate it as the sound is driving me nuts and it's kind of sad that I can't take my family for a ride because the noise is extremely annoying while you're riding.

Thank you all for your input and I hope to hear back soon.