My LOS Dec 26th 1968 Z28 Looms, Plug Wire Supports
UPC 6 / B5
V-8 Spark Plug Wiring, coil & Shields.
They are "part of the engine assy"
are BOTH stamped "GT" mfr markings.
I would imagine there are a variety of Mfr.s for the part.
I "THINK" the 302 Motor Driver loom-support is specific to the Z28, as in Shape, direction contour etc.