Thanks guys.
I replaced the links yesterday. The job turned out to be much more difficult than it appears.
@t-rd is spot on.
The main problem was that the bolts were very hard to take off. With the 5mm allen wrench in place, I was able to loose the bolts. But removing the bolts is another story. As the bolts got loose, they started to wiggle. The allen wrench easily could strip the hex hole!
Unfortunately, I don't have a thin jaw vise grip to prevent rotating. I had to cut the bolts off!
Due to limited access space, I had to rely on a hacksaw blade (yeah, just the blade.) to cut one off. The other two, with the hacksaw. It took me more than 1 hour to cut the links off. While at it, I kept thinking about those 2 NY jailbreakers recently in the news. They basically used 1 hacksaw blade to escape.
The following are what I've learned:
(1) Thin jaw vise grip seems a critical holding tool for this job.
(2) be prepared to cut.
(3) This tool came handy for this job: GearWrench x-beam XL 14mm racheting wrench.
The rear suspension noise is gone!