Si, those are the studded metal retainers - my bad. In that case, my flares must be cut differently because the MJ front wheel wells were all the same AFAIK. I remember when I installed them I had to bend them up to get them to snap in under the flares. I'll take some better pics today - it's not an optical illusion.
Also, the p/n's were different between years, but I think that's because the liners were made out of different materials:
87-90, 55001890-1, PANEL, Inner Protective
91-93, 55027152-3, PANEL, Inner Protective
94-96, 55175008-9, PANEL, Inner Protective