I have a Hidden Hitch Class II trailer hitch for sale. It also comes with a Class III adaptor which makes this a pretty good combination.
This hitch will fit on the Caprice wagon, Buick Road Master wagon and Oldsmobile Custom Cruiser wagon from the 1980's up to 1996.
I personally used it on a 1989 Caprice wagon and 1995 Caprice wagon.
If anyone is interested in it let me know. I don't have the mounting kit (bolts and screws) for it but you can pick something up from a hardware store.
100.00 shipped