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I have a question regarding prefix and date codes. I have a 1970 Mach 1 and trying to find out if the AC compressor is original to car. The car came out of the Dearborn plant in December of 1969. It has York compressor. I would have expected it to have C9 or D0 prefix but it has C8 prefix. However, the date code on the tag 079K.(October 7th, 1969) I it possible they would have put a C8 part on a 1970 model? Thanks
You are confusing part numbers with date codes. They didn not change the part number every year, only when there was a significant revision or a new part. You will have C5, C6, C7, C8, C9 and D0 prefixed part numbers on your 1970 Mustang. Maybe even earlier ones, Eg possibly your lug nuts.
These are different engineering numbers for AC compressors that are interchangable and appear to be the same other than the prefix. C8AA-2875-A2, C9AA-2875-A2 & D0AA-2875-A2. So why would they use an AC compressor with a C8 prefix on a 1970 model when there are more recent prefixes for the same compressor? This is why I question whether it is the original compressor.
Something to keep in mind is the the vast majority of compressors used at the Dearborn plant were the cast iron Tecumseh. By contrast the vast majority of service replacement compressors are of the aluminum York variety . The most logical explanation for a C8 marked York compressor ending up on a 1970 instead of a C9 or D0 compressor is that it was replaced with a service compressor.
Engineering numbers(what I call them) that are found on the part are typically different then the part numbers that are used for inventory found in the MPC. The MPC will sometimes list the engineering number to identify the part also.In this case we are discussing what is typically found on the A/C compressor.
My thoughts exactly but when looking at 70 Dearborn cars I found many more Yorks than the Tecumseh. Maybe something changed that year Guess I could look at what the majority was (in my sampling) for 71 as a possible indicatorFor others, overall it was easier to store the York style compressor since they didn't have the same rust issues since they would be sitting for years on the shelf and the since they weighed so much less that made moving around, storing and shipping much easier