Instrument cluster differences? Year Span?

I have an ex drag car that came without a wiring harness. I have an unknown cluster (87-93) style that I bought on eBay a few years ago and did a dash upgrade on my 86. I wired it up in the 86 so I would just have lights, brights and blinkers.

On my 91, I bought a 91 harness for it and the cluster is clearly not made for this harness. Where the inst. light is on the harness the part on this cluster is ground and the blinkers are also going to the wrong wire.

So, I think I have a different year cluster, I didn't know there are different year clusters. Anyone have any idea on what years changed?

My harness matches this diagram:

http://www.veryuseful.com/mustang/tech/engine/images/mustang-87-93_Instrument-Cluster.gif

Thanks,

Scott

Found this and it answered and helped me a bunch: http://www.stangnet.com/tech/cluster87-93.pdf