There were two 428's. In 67, one had 10.5:1 compression ratio and had 360hp. The 428 HO had 376 hp. They had forged steel cranks. In 68 and 69, the one with 10.5:1 compression ratio ran 375 hp at 4800 rpm and the one with 10.75:1 ran 390 hp at 5200rpm. The were only options for the full size ponchos; Catalina, Executive, Bonneville and Grand Prix. No expert here. Just quoting STANDARD CAby kelly c - Pontiac GTO Forum
traviswilliams quoted: "a 428 that was made for only two years" Maybe that was a typo but, the 428 was produced 67,68 and 69.by kelly c - Pontiac GTO Forum