Wiper motors in the Fiero differed depending on the "intermittent" or "pulse" action.
'84: Accoring to the Hollander manual, the'84 Fiero did not have a pulse wiper. However Jim Teague, the original owner of an unmodified '84 Fiero, advises that his car has an intermittent wiper motor. So it appears at least some '84 Fieros came from the factory with the upgraded motors. In any case, the cars below had wiper motors which can swap with the '84 Fiero:
Blazer/S10/GM Jimmy S15 '83-84 Blazer/S10/GM Jimmy S15 '83-93 without pulse wiper Buick Skyhawk '82-83 Buick Skyhawk '84-89 without pulse wiper Cadillac Cimarron '82-83 Chevy Cavalier '82-83 Chevy Cavalier '82-94 without pulse wiper Olds Firenza '82-83 Olds Firenza '84-88 without pulse wiper Pontiac 2000 '82-83 Pontiac 2000 '84 without pulse wiper Pontiac Astro '85-89 without pulse wiper Pontiac Safari (GMC) '85-89 without pulse wiper Pontiac Sunbird ' 85-94 without pulse wiper S10/S15/GM Sonoma '82-84 S10/S15/GM Sonoma '85-93 without pulse wiper'85-88: with pulse wiper. Those without pulse wiper had the same motor as '84.
Buick Skyhawk '84-89 with pulse wiper Cadillac Cimarron '84-88 Blazer S10/GM Jimmy S15 '85-93 with pulse wiper Blazer S10/GM Jimmy S15 '94 Chevy Cavalier '84-94 with pulse wiper GM Syclone '91 GM Typhoon '92-93 Olds Bravada '91-94 Olds Firenza '84-88 with pulse wiper Pontiac 2000 '84 with pulse wiper Pontiac Astro '85-89 with pulse wiper Pontiac Astro '90-93 Pontiac Safari (GMC) '85-89 with pulse wiper Pontiac Safari (GMC) '90-93 Pontiac Sunbird '85-94 with pulse wiper S10/S15/GM Sonoma '85-93 with pulse wiper