The driveshaft fell off, shop repaired it, fell off again 2 weeks later. Cause?

Hi, my name is Devin. I am an auto repair expert with the Car Genius team here at RepairPal. So sorry to hear you're having trouble with your Trailblazer. If your driveshaft fell off twice after being repaired, the root cause could be improper installation, defective parts, or a deeper issue like misalignment of the rear differential or transmission. When the driveshaft is reattached, the bolts must be properly torqued to stay secure. If the bolts weren't tightened correctly or the yoke or U-joint wasn't aligned properly, it could cause the driveshaft to come loose again. There's also a chance that the differential or transmission mounts are loose or worn, causing excessive movement that leads to the driveshaft disconnecting. If you need more advice, have any other questions about your vehicle, or would like to get connected to a RepairPal Certified shop near you, we have you covered. Give us a call at 877-913-1554, and we will happily help you out!