GM HEI and DIS engines Can
use better plugs but can hate other "better" ones like Many Gimmick plugs that cost more and do nothing if your lucky. DIS Hates
BOSCH +2 and +4 and others. Some may remember Split Fire and others got sued by FTC and more for false ads and even wrecking engines.
Main thing for Fiero is use better plugs w/ nickle etc coated metal shells that are way more rust preventive then most standard copper plugs. You find water just from washing can rust Fiero plugs easy.
HEI can use any basic Platinum plugs from ACDelco and some others. Fiero V6 ACDelco 1 Rapidfire (Yes 1 is the PN)
DIS can use "Double Platinum" plugs from ACDelco or Autolite. These put Platinum on tip and ground arm so ones that fire backward sees exact same setup. Example: 87-88 L4 can use AUTOLITE APP666 or ACDelco 41-816 Double Platinum Spark Plugs.
Note: RA and some others has NOS of older plugs or simple have wrong data. I get plugs locally and check I get right part before leaving store.
When removing plugs for any reason use compressed air and a wire to stir up and blow out crap before you use a wrench.
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
The Ogre's Fiero Cave