OK the mount could be the problem, if it is common to make noises while on the brakes at a stop. The when going in reverse i have heard #(thunk) but i always figured it was crap in my trunk cause my trunk if full of everything from parts, tools, to subs and bottles of ATF and oil.

Is there an easy way to figure out what is the problem, or would it need to be jacked up and have a close look at them all.