I remember reading Colin Shipways book and thinking it was full of nice pictures, but its alot of the text was innacurate. There were the 3 different types of bumpers used on the Z in the US market. There was the 240Z type bumper that non US cars had right up to 77. Then there is the extended bumper that has the shock absorbing dampers. (pics/diagrams in the Haynes manual). Then there is the thick style bumper that the 280Z had. Also the 2+2's had a longer wheelbase, and are wider at the rear (referring to the body, not the track - dunno if its different). Thats why 2+2 tail panels wont fit the 2 seater. If you compare them the 2+2 has 2 vertical indents either side of the licence plate, the 2 seater doesnt, as the gap is smaller. There are othe changes that appeared in later models, like the lip on the rad support panel. Dashboard changed on the 260Z.