It was a bit expensive chasing down the major problem. The suspension components were a mess and systematically replaced: Stabilizer pins all around; coil springs and struts front end; rear stabilizer bar bushings; leaf spring bushings all around; rear drive shaft; engine and transmission mounts and the list goes on...Bought from a dealer whom told me it needed only universal joints...Right off within a week started noticing alot of rattling and thumping when going over bumps and thumping in rear and in front when after coming to a stop and then taking foot off of brake. Finally, a guy put hands on rear drive shaft and pointed out that he can turn shaft more than an inch before any rear wheel will start to move. I fail to realize why a rear end issue cause thumping below the front seats, yet still...My state has a total of 9 rear end shops and I called all of them. I hate it when they say this or that is wrong when they haven't even ridden in the vehicle nor pulled the rear plate for an inspection! Generally was told I was looking at from 750. up to 2350. depending on what is the exact issue/s. 350. is the general cost for an inspection whether having it fixed or not. Used rear end plus cost of installation generally 1200. all said and done and no guarantees. The best solution I found: Junk the car! I would like to point out that this is the 3rd Chevy product in a row that either came with or began shortly after ownership rear end no good! 1989 Firebird w/31,000 miles, 1995 Firebird w/67,000 miles and now this trailblazer. The trailblazer came with multiple problems and I fixed several of them and then the next week something else has to get repaired. Considering that the kelley blue book lists the value of this truck in excellent condition as only 1650. ( I now know to always look before paying and closing deal!) I junked it. I found out just 2 days ago that the awd system doesn't work at all as well as rear end issues. Lesson learned: Stay away from Chevy products and stay away from any make, model and year that has 4 wheel drive which are very prone to failure even on new cars less than a year old.

Update from Jan 26, 2017: Discovered that the thumping under the seats is yet another issue. Where the front drive shaft goes into yoke there is an inner problem within that component as well. Am told to replace the transmission! I have yet to ever encountered an honest used car dealer in Rhode Island. They all can do whatever they want being that there is no such thing as any lemon law in RI unless the car has under 36000 miles upon it. Dealers know the laws better than the state and lawyers do and so they can exploit anyone and get away with it. Even down to taking your money, not delivering the car and keeping your money ( this also happened to me at the hands of Distinctive Motor Cars on Plainfield Street in Johnston, RI who took 3622. dollars and refused to give me the vehicle claiming to me the credit card company used never paid them yet the card company proved that they did pay them).