As promised, here is the Assignment Card for #E408306 -
Using this
CHP Office Finder, the car was initially assigned to CHP Office #126 in Garberville, CA, but was immediately exchanged to CHP Office #150 in Ukiah, CA (Northwest of Sacramento). It replaced a 1982 (#E870580), and was replaced with a 1987 (#E422957). The scan doesn't show it well, but you can see on the card where the writer started to describe #8306 as a Dodge Diplomat. Since this car has one of the lowest known Unit Numbers for 1985, I could see where he/she would have written that out of habit (much like dating a personal check in January with the prior year).
So I will send the card to the seller so he can include it with the car when he sells it.