Special Equipment license plates appeared in the mid-1980s. They are used on construction equipment. I am not sure what the distinction was between this type and “Construction” plates, or if these plates replaced “Construction” plates for a short while. This type was continued on motorcycle-sized light blue plates during the general reissue in 2000.
Numbering on the older style appears to have reached around 1800 or so.
“Special Equipment Dealer” (Dealer SX) plates are not directly tied to this type – it is more of a coincidence that they share the same name.
ca. 2000s blank