Stabilizer Bar: The '84-87 Fiero uses a 23 mm diameter stabilizer bar in the front but not the rear. The front Stabilizer Bar from an '87-99 GM H-body car (Bonneville, Olds 98) will fit the '84-87 Fiero.
New sway bars are available from the Fiero Store. A slightly larger 1" bar (25 mm) is available from Addco through AutoZone. The AutoZone part number is 758U (delete the "U" if you do not want urethane bushings) and it must be special ordered.
The '88 Fiero used a stabilizer bar in front and in the rear. We have no information about other cars using the same bar. New bars for the '88 are available from the Fiero Store. We have read that the front stabilizer bar on a 2000 Grand Prix will fit on the rear of the Fiero. We suspect that is true for only the '84-87 Fiero but do not know.