The 260Z replaced the 240Z in 1974. Only one configuration was available at first which was a 2-seater sports car. The car shared the same 90.7 inch wheelbase as its predecessor, but had an increase in engine size. It also gained weight, creeping to 2400 lbs.
A 2+2 seating arrangement was added as an option for 1974-1/2 cars. This layout increased the wheelbase to 101.6 inches. Curb weight was also bumped, to 2670 lbs. The smaller standard 2-seater was still offered though.
The 260Z was sold alongside the 280Z in 1975, though officially these were still 1974-1/2 cars. The model year of 1975 is occasionally thrown out there for these late 260Zs though. The model name did live for a few more years outside the U.S.