i came across 2 different types, both circa 96 and both with same factory stampmarks/numbers on the wishbones
1 had a steel casing (27.5mm ?), and 1 had a tapered/stepped socket on the wishbone (27 + 30mm)
you have to bear in mind that that bush locates the wishbone in a fore and aft direction, and any movement towards the front or rear badly effects the tracking (i speak from experience )