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As time goes by rear calipers on 1982-92 Firebird TA & Camaro's might come up for attention and as in more then a few cases over the years sometimes cars have had unknown alterations done.. complete diff swaps and just miss-spoken detail about which REAR factory caliper they have.
This may help ID easily at least the Factory TWO used..
From sometime in 1987 the Australian Produced under License finned type rear caliper was installed on most GTA's & TTA's.
Otherwise they were the cast iron flat top type ... see below for visual help.