[Poncho Dave]

Refinishing the undercarriage of a 77. The rear floors under seat use the same round plugs found in the trunk drop offs. The plugs in the drop offs are a turquoise color. All the rear floor plugs I’ve removed are rusty and look like clear zinc under the seam sealer. Could someone confirm the color of the rear seat plugs? Not sure why GM would use two different coatings for the same plugs, but anything is possible.

[TAKerry]

The turquoise colour you are seeing is most likely from the trunk paint. My 77 had an aqua coloured speckled paint as a factory finish. It is my understanding that the cars were dipped in primer and these holes allowed the excess to drip through. I would think maybe that a clear zinc would be the correct 'new' finish. Also, just an idea, I would think that once the plugs were installed no further finish would have been applied on the int. side. Underneath would most likely have undercoating if applied. Personally I have never seen them that weren't rusted.

[Poncho Dave]

Pretty sure the plugs in the drop offs are turquoise, but all others are pretty rusty on my cars. Under the rear seat and trunk plug looks like it must only be clear zinc. Just wondering if anyone noticed the same.

[Aus78Formula]

Were there slightly, different diameters used and colour a quick reference on production line?