Non of the 3.5 RR had anti rollbars or the even the facility to fix them. that came in with the 3.9s although there was an aftermarket item available that came with clamps which I saw advertised back in 1987.
STC 8046 is listed for 1992-95 JA onward VIN RR as a sports suspension kit.
Harvey Bailey sounds familiar maybe it was this that was advertised in LRO in the early days