 This year the badges changed from "Z/28" to "Z28".Horsepower ratings continued to drop, not only due to lower compression and tighter emissions controls but, beginning with the 1972 model year, a switch from gross (on dynamometer) to net ratings based on an engine in an actual vehicle with all accessories installed.With that, the 350 ci LT1 dropped from 330 gross horsepower in 1971 to 255 net horsepower for 1972 and the big-block 396/402 was now rated at 240 net horsepower compared to 300 gross horses in 1971.