I am working on a friend's '90 3500 4x4. It is leaking at the oil cooler adapter. How do I remove the adapter? My stepson got under there on Sat and removed one of the pipe plugs on the bottom of the adapter, but saw no bolts. This is leaking pretty bad, so we need to get it removed and new gaskets installed. The Chevy Service manual was useless. Can anyone help??