Plastic Oil Pan on 1980 Cadillac

I have been told that Cadillac Experimented with a production oil pan on a 1980 model.  Has anyone heard of this or do you know who might be a good resource for this information?

I know of plenty of plastic engine parts, intakes, valve covers, timing gear covers, timing gears, air filter boxes, radiator tanks but have not heard of a plastic oil pan yet,