Dan, they are not made anymore, but can still be found. A pair sold on eBay yesterday CHEAP.
Bearings for the 66 GS (different pn) usually cost about $45 each.
Part number is:
RW507A
RW507AR includes the retainer.
Buick - 1965 - LeSabre
Buick - 1964 1965 - Special/Skylark Skyroof Station Wagon (Sport Wagon), 65 GS
Oldsmobile - 1964 1965 - F85 Cutlass Station Wagon, Skyroof Station Wagon (Vista Cruiser)
A source I've heard many times is Olcar Bearing. Do a Google search and you'll find the phone number.