Ok - found the oil pressure sending unit. It's on the oil filter cannister - and I could access it from under the LH side of the car - directly under the filter cannister.

There's a single black wire that comes out of the sender - the unmolested wire then feeds directly into the firewall (along with another wire bundle).

What would cause the gauge to peg? Clogged unit? Clogged 'passage' to the unit? Maybe I just need to pop another sending unit in place. I'd appreciate any advice. Thanks guys!!