Z Tech Tips Lowering a 280z rear or raising a 240/260z rear
Swapping the rear strut mounting insulator from an early 240z or 260z to a later 280z will drop the 280z ~ 1" without affecting suspension geometry.
You can also swap a tall into a short to raise the rear of a 240z or 260z.
"Short" 240z/260z on left. "Tall" 280z on right.