GM Genuine/Acdelco is confusing. Here’s an example. First picture shows part on Acdelco site. They are listed together and as same part. I even emailed them and they confirmed it’s same part.
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But on many sites, including RockAuto, they are listed separately and the “GM Genuine for considerably more.
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DISCLAIMER: I have no real evidence to back this up, just something I'm inclined to believe based on my observations regarding this subject...
I think a lot of that confusion comes from suppliers choosing which part number (GM or ACDelco) to use when creating the listing. People are used to paying more for the OEM GM parts, so the distributors will separate them by part number even if they're the exact same part.
For example... I was researching multi-function switches for the 'burb today (posted another thread in the Audio + Electronics section, cruise control issue) and noticed this same thing. If you look up the GM part number on GM Parts Direct or Wholesale GM Parts Online, it's $330. If you look up the ACDelco part number for the exact same part on RockAuto or Amazon, it's $200.