In the second picture, if that's the vacuum pump under the radiator hose, it looks like it has screws holding down the cover. It might be one of those oddball mid-series pumps with an open bearing but screws holding down the cover. There was a listing of such a beast on eBay a few years ago. For the cost of a gasket and an hour's work, check to be sure!

Sixto
87 300D