Exhaust rattle '86 Delta 88
 

Does this vehicle have a heat riser similar to old V-8's that would be rattling at idle or just off idle?
I already have discarded loose tin shield over the cat converter but wondering what else is rattling just behind engine? Can this be cat internal?

You might be able to locate it with some assistance from a helper. First, block off the drive wheels with something. Next, have them get in the car and make sure the emergency brake is firmly set. Then, have them start the car and put it in gear at idle while you poke your head around in the engine bay. If it needs to come up just a hair above idle, have them firmly apply the brake (plus the emergency brake is engaged) and apply a little gas with the brakes firmly pressed.

You could try using a long breaker bar or your hands (wear some gloves) and try pressing various areas where the sound seems to be coming from. If it's a loose part, you'll know where and what it is when you stop the rattle by applying some mild pressure to it. You'll also be able to feel the vibrations when you locate the offending part.

Definitely use extreme caution and be safe while you're tracking it down.

Thanks for replies. An update to original thread. Found after some experimentation that my rattle was emitting from Catalitic (sic) converter. The inner material of converter that looks like a honeycomb was breaking up and partially disintegrating causing the rattle near idle or just off idle. At speeds it had enough pressure to not make noise. Replacement of converter eliminated noise.