Attached in the 3 photos are 3 LH Upper Spark Plug Wire Supports. According to my research as well as using my 1969 and 1970 Chevrolet Parts Catalogs (Oct. 1968 & Jan. 1970) I have determined the following:
1. The support on the left is GM # 3932485 listed for 69 ALL (302, 307,350). This support has 3 different angle bends with a 0.80" diameter hole and I believe that this support was only used on the 1969 Z28.
2. The support in the middle is GM # 3932487 and is also listed as 69 ALL (302, 307. 350). This support has only one angle bend with a 0.80" diameter hole and I believe that it was not used on the 1969 Z28.
3. The support of the right is GM # 3973366 and is listed as 70* ALL (8 cyl.)(exc. 454) . This support has only one angle bend with a 0.92" X 0.78" oval hole. The asterisk (*) following the year indicates a new 1970 model part. This support is also used on 1971-1973 models as listed in my 1971, 1972, and 1973 Chevrolet parts catalog.
According to GM Parts History (for service parts sold over the counter) GM # 3932487 was replaced by GM # 3973366 in June 1974. This makes sense as the two parts are almost identical except for the shape of the hole.
I would appreciate any comments to either confirm my research or not.
Dave
