zMarkk

I have a 2005 v6 with about 80,000 miles on it, and there is a weird sound(like a metal ball is bouncing around in a tin can) in the rear right (passenger) side. It starts making that noise when i accelerate, but it only happens 3/4 of the time. What could it be?

Hotwheelracer

I am no mechanic, but have you looked at the muffler?

zMarkk

That might be it o.O

tx_zstang

,check the exhaust pipe over the panhard bar, too; it's probably rattling. Or a muffler hanger cane out or broke, etc.
Could also be suspension related.

mystangisblack

I'm also hearing something similar, sounds to me like the muffler is hitting the bottom of the car.

Nuke

Also try torqueing the axleback clamps just before the muffs about 1/8-1/4 turn tighter. And look at the heat shields for contact with any exhaust component or looseness.

Alec

Could be your cats going bad and blowing metal pieces out the exhaust

Mr. Ugly

That happened to me.

Broken hanger on my Pype Bomb.