And is this Chassis Parts Illustration for the Skylark Gran Sport, it shows the brackets being the same hand (as Chuck stated) and, in looking a view B, it also calls out 2 brackets having the same part number. I'm kind of thinking both versions were correct - depending on where the cars were built, maybe when, and what brackets were available at that facility.
Also, from the same reference, the LaSabre, Wildcat and Electra used the same part number for the bracket, clamp and insulator. So at least from this source, LaSabre's, Wildcat's and Electra's are sources for the same part (unless opposite hand brackets are understood to the the only version correct for the 65 GS).