Sorry, I didn't see the rear brake drum. That would make it a 1970 model. It could be a GTO 300 (Blue paint, 3.5 hp with painted fenders), a GTO 500 (White paint, 5 hp with painted fenders), a LTD 230 (Forest Green paint, 3 hp with painted fenders, or a LTD 330 (Red paint, 3.5 hp with painted fenders). These were the only models with 6" steel wheels that year. In 1969 the steel wheel models had a band brake on the clutch. The GTO 100 and 200 models had 4" steel wheels, yours appears to have 6" wheels.