Oil pressure sensor, oil cooler lines, oil filter adapter, rear main seal, oil galley plugs.
You probably already know this, and I don’t know what version you have, but the later models, like my 2000, don’t use the adapter that mounts the oil filter horizontally. It just uses a shorter filter that is vertical and seals directly against the block.
Also make sure it’s not something stupid like the old oil filter gasket from the last oil change got stuck to the engine and didn’t get discarded with the old filter which would make a double high seal and usually will blow out and leak. I know you said it’s coming from up higher than the filter, just putting that out there for others.