Jim, the Drawtite hitch you bought (p/n 75014) was designed for the 86 MJ longbeds. When the 87's came out with the shortbed MJs, the design was changed and the Drawtite hitch p/n changed to 75021. The 75021 fits both long and short bed models. I have the 75021 on my 91 longbed, and used the spacers that came with it. Looking at pics between the two models, you can see that the side plates are cut very differently. I'm guessing there are some differences between the 86 LWB and later model LWB rear frames, or Drawtite simply changed the design to accommodate both models. :dunno: