I have an 89 oldsmobile 98 that I just put a used transmission in. The car has a 3800V6 and the trans is a 4T60, also known as the 440T4 hydramatic. The trans shifts well, but there is a rattling that sounds like it is coming from the trans, between the engine and the firewall. It only is there at idle. When I shift into reverse or drive it goes away, and then when i'm driving and start slowing to a stop I hear it again. Anyone have any experience with this?