Chevy dropped the IROC package
for 1991 and brought back the Z28 as the top performance model. The styling
changes were small but made all the difference, with a taller rear wing and gorgeous
new ground effects with redesigned 5-spoke wheels.
The new B4C package was built for police forces, and was basically a Z28 with
the 1LE options packaged as an RS... very few were built, making them quite