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Can anyone tell me whether either of these is the original design for the push-in oil cap on a '71? The one on the right (2) was in my engine when I bought the car. I'm replacing it because it's torn with part of it missing on the inner flange. I bought the one on the left (1) from a gent on ebay who had it listed as NOS. Is this correct?
NOS doesn't mean assembly line. #2 appears to be assembly line (fat O) #1 is a later replacement (skinny 0). What I do not remember is if there were height differences in the assembly line caps, or if all assembly line caps were short (I'm thinking they were all short, but thats just a feeling).
Replacement oil caps often had the word OIL in thicker, bolder letters or with a narrower letter O. A small sampling of NCRS Judged vehicles indicates that the Tonawanda engines may have used the shorter caps while Flint engines used the tall caps. To date, no pattern has been established.
Total research not completed but the under standing now is. The taller cap was used on Flint small block engines while the shorted one was used on Tonawanda big block engines. The elliptical "O" is later service type.
GM usually had at least two vendors approved for every part. This prevented vehicle production shut-downs due to individual business 'disasters': weather disasters, financial closings, fire, union strikes, etc. It is highly unlikely that either Flint or Tonawanda used ONLY a specific vendor for all of their production.
'71 Oil Cap
