They're a half year only deal, from the later portion of '90.5 going into '91. Unicorn in the sense that they accept the wiring harness of the moonie cluster yet have the needle style of 91 and up. This allows the early crowd to run a cluster with a tach with minimal fuss. I've heard that if you have a '90 with a moonie, the unicorn cluster is a direct plug and play, not sure if you have to add a signal wire for the tach. If you've got a '91 and down, you have to move a few wires around and run a signal wire for the tach. Only PITA is the speedometer. Depending on what the unicorn cluster came out of, it might need to be recalibrated. Pretty straight forward swap though and if I can do it, anyone can do it.