Rattle in Drive

There is a loud, low tone rattle when I'm stopped and
holding brake. When I let the brake off it stops except
for maybe a couple more rattles. Today I noticed when
I was stopped and I put it in Neutral, it went away.
Any advice would be greatly appreciated. My Mother
is coming to visit and usually borrows the truck.
I need to fix right away. I will see if I can get someone
to hold brake while I look under when I get home
from work but that's late. Thanks

Can't say if it's your problem but I had a similar sounding rattle in my old suburban. Finally tracked it back to the heat shield above the catalytic converter. Several of the mounting points had broken free allowing it to rattle. Once I got it anchored back down all was well.

Thanks, I went out and gave a quick look and didn't see any shields or
exhaust loose. The only thing I saw was that the little tube that comes
out of the cat is directly against the shield next to tranny pan. I'll look
closer later. I can feel the rattling through the floor.

Like IDMETRO states, it is probably something in the exhaust system. You dont give any more detail, but I am going to assume that you only hear it at idle at a stop. Also check all the mounting points for the exhaust - sometimes one will rot thru and rattle. Just make SURE that while you are checking that the EBrake is on and the wheels are chocked - its very dangerous to be near (esp UNDER) a vehicle in Drive that is not on a lift. Good Luck!
GOLIATHGMC

I would lay money on the heat sheild between the starter and the passenger side exhaust manifold. My 88 rattled like hell untill I took it off.