So, it looks like the culprit of the mystery rattling sound was indeed the rear axle bushings (inner). Any idea where I can purchase replacement bushings, both inner and outer, for a Renault Alliance? I heard that the outer bushings are part of the mounting bracket and that the entire mounting bracket needs to be replaced?

try this be4 you go the bushing route.

in between the two inner bushings, drill a small hole, and screw in a self tapping grease fitting. then pump it full of grease, at least 100 pumps of the grease gun.
that fixed my car up perfectly. no noise or anything.

Rob

Just a little word of warning:

Ideally you should use a grease suitable for rubber parts, as ordinary grease can damage them in a long run(get all soft and spongy).

Authorised service dealers here in Finland fitted grease fittings to the rear axles when new, just like Rob is suggesting to prevent the noises. The correct brand Renault suggest for this is Molykote (can't remember which type...)

Unfortunately, the correct Molykote rubber grease is expensive as 'ell, so even many authorised dealers skimped on this and used ordinary grease instead. After all, a regular customer won't take the rear axle apart to find the scam...
But I found this out when I took off the torsion bars: the rubber "jackets" protecting the bars were covered in regular grease and gone all soft and swollen. I can imagine how the center buhing must look like... I suspect this is one of the reasons the rear wheels seem to live lives of their own in longitudinal grooves: the inner center bushing's gone soft allowing too much sideways movement of the trailing arms...

Summa summarum: Greasing can stop the noise, but wrong type of grease can cause unwanted side effects in the long run.

Yeah, that's pretty much what I'm experiencing now -- the rear of the vehicle seems all over the road and difficult to control. I would like to add the grease fittings; however, seems like the rear buchings are pretty much toast -- at first it was just a rattle, now its a loud rattle and the vehicle sways in the rear.

So, back to my original question, where can I find the replacement bushings in the U.S.? Or where can I find someone overseas that will ship to the U.S.?

Hello if you need to purchase bushings, a new set can likely be had at Alpine Renault in Quebec. He buys parts right from Renault Group, and is a reseller to the public, via phone or internet.

the website is http://www.alpine-america.qc.ca/

He does not speak the best english, he is French afterall, but he is friendly, and he gets the stuff you need. I have ordered from him before and he's very friendly and willing to help.

Michel Guegan is his name.

Hope this helps!!
Rob in Toronto.