whats the difference between the irocs and the z28's? such as the 91 or 92 z28? affter the iroc was gone wouldnt the z28 get the iroc stuff?

 

As we know the IROC started life as a handling/appearance option(RPO-B4Z) for the Z28 in '85.Then in '88 to mid '90 the IROC became the performance model of the line but it still contained RPO-Z28.Essentially the "base" IROC was the previous year's Z28 with the LO3 and the 15" 5 spoke wheels.The LB9 returned for '90 as a no cost option as did the 16" wheels.Midway thru the '90 model year Chevrolet didn't renew the contract with the IROC series.The Z28 returned as the top model but with as a '91 model early with the LB9 as it's standard motor.The biggest exterior difference between them would be the Z28's hi-rise rear spoiler(did the '90 IROC receive this before it was discontinued?)and the return to just Z28 exterior badging.

I know I've left info out but this is my understanding of them.Hope it helps.