I took a look at the rear 68 shaker that I have and it is for the RH side. It is in very good shape, still has the speckled painting on it that you see inside the trunk area. The bolt that goes into top of the shaker does not look like the original bolt, it looks newer.
Shoot me an email Brian if you are still interested. But remember, I only have the single shaker, not a pair of them.
