Chassis Squeaks

[Passport1]

My 2006 Saab Combi, 97K miles has developed a chassis squeak. It is definately not a clunk or rattle and seems to come from the aft end of the car. I did the rear brakes about a month ago but no untoward noises after I finished. The noise seems to come from underneath but it is difficult to be sure.

Things I've done;

took all the tools and spare tire out, no change
put the back seat down in the cargo position, ditto
working from top down, silicone sprayed all the door seals, lock striker plates
underneath, sprayed all the suspension bushings, exhaust hangers and body to sub- frame bushings
The only thing that so far mitigates the noise is the volume knob on the radio.

How do you deal with these elusive automotive gremlins?

Unwinnable

 

[RoadDukie]

Sway bar bushings are a common cause of squeaks. Some grease netween the I/D of the bushings and the bar usually works.
Not sure if you hit these when you said that you sprayed the suspension.

 

[StumblingElk]

Did you check/spray the rear trailing srm bushings?

 

[Danno]

Try adding some felt or cardboard under the trunk lid stoppers, see if that changes anything.