From the Sticky in the S30 Section:
Interior. In general terms there were two distinct interior designs. The 240 was one, and then the 260/280 was the other. The 240 didn’t have to many interior changes through its production. The 260 interior was totally revamped. The 280 retained the 260 interior. In ’76, the shoulder belt mount point went from the “C†pillar to the strut tower, (seat belt doesn’t dig into your neck as much on the ‘76+ cars). Also, in ’76, the AMP gauge became the Volt gauge with a fiber optic charge light. In ’77 the only significant interior changes were the font style of the gauges and the doors received a total redesign internally, which relocated the window crank and the door lock switch. The door changes in ’77, (which carried over to the ’78), made for much heavier doors, but the window regulators were much smoother and the actual door striker design was totally different than the earlier ’70-’76 doors. Doors for the ’77-’78 will not interchange with the earlier doors due to the different striker design. In ’78, the speedo received KMH in small blue print. Either in ’77 or ’78, under dash foot well lighting was also added. In ’77, the Z received larger capacity fuel tank which encroached on the spare tire well necessitating the space saver spare, (the 240, 260 and ’75-76 280 received a full size spare tire), and also the ’77-78 rear hatch area now has a raised false floor which was to accommodate the larger fuel tank and that little deflated spare. Depending on which manufacturing plant the ‘77/78 was manufactured in dictated how the that false floor in the hatch area finished out to the rear. Some were flat level all the way back, others kicked up at 45 degrees to the hatch.
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