I didn't doubt you, your lift is obviously older than the truck and its an oddball piece. The lifts were still called Skyworkers in '80 so your lift is gotta be the end of the Skyworker brand line or the very beginning of the ALC's.
It has the steel upper and lower knucles that was the fix to the bad aluminum ones back in the Skyworker days.
Does the tag say Aerial Lift Repair or Aerial Lift of Con.?? High pressure upper controls or low pressure???
The stinger is more of a tell tale ID to the Skyworker brand than it is to a ALC