edit........... aw crap! Ron beat me to it!
Paul,
I think what you need to do is get the manual regulators from a 1978-89 car. If your car is a coupe, the replacement regulators must be from a COUPE. Call up a dismantler or post a WTB ad for them specifying they must be 1978 or newer COUPE regulators (manual).
I say 78 or newer because the PET says 74-77 regulators are a different part # than the 78-up ones. I tend to trust PET more than the tech reference that Ron posted- even though the part numbers sorta agree. No offense Ron!
#'s for 74-77, per PET, are different than what Ron's post shows, but agree with the #'s from 78-up. So i'd ask for 78-up regulators since your car is a 1980.
Part numbers are:
Left = 911.542.929.03
Right = 911.542.930.03