I have this ratting/squeaking nosie coming from the rear of my blazer. Only happens on acceleration and goes away around 40mph. Doesn't do it all the time but has gotten worse today. Noticed it yesterday. My guess is rear u-joint but some are saying cat. It doesn't do it at idle or in park so I assumed it wasn't the cat. Blazer is an 01 zr2 with 184k miles. Any ideas?

 

Sounds like something's loose in the exhaust system to me. Have you climbed underneath and wiggled stuff around? Any bad u joint that I've seen clunks when the drive shaft starts to move...

 

Im about to go try to figure it out, had to work till midnight last night. If it were exhaust system i would think it would make the sound in park. But it doesnt do it in park, only while driving and only while on the gas.

 

This is what i found yesterday. Looks like one of the caps on the rear u joint lost the rubber seal and is starting to fall apart. Weird thing is there is no play in the driveshaft. Plan on changing the u joint out on thursday.

 

Sounds good, thanks for the update!