The 260Z was available only during the 1974 model year as a transition year with a minor displacement upgrade to overcome more restrictive pollution requirements prior to the conversion to fuel injection in the 280Z.
Early production 260Z's can be found assembled with 240Z parts as a strategy to use up remaining 240Z parts production identifiable by their thin chrome bumpers and late production 260Z's were assembled with what would become 280Z parts and are identifiable by their "big bumpers", DOT required 5mph bumpers. Although these are the most noticeable differences there are a myriad of other less obvious transition year parts.
This mid-year transition makes maintaining, repairing, upgrading and modifying 260Z's an adventure in itself.
Many consider the early 260Z's the most desireable given their compatibility with their predecessor 240Z's components.