First thanks for bringing this back up to the top. One of the side benefits of asking new questions in an older related thread it appears. Back when this threads was started I don't think I had any build sheets for the 390 4 speed no AC application but currently I do and can confirm that this one had the C8OE-B installed originaly
However, the blade "marked C8AE-D" (C8AZ-8600-D) is listed for 390 with "extra cooling" "hang-on A/C"
There is nothing listed for a 390 with factory "select-aire" A/C. Can someone help with that?
Can't help with the dealer installed AC question since that would not have been installed at the factory. We would need a number of original cars with the right combination that matched to confirm since I don't think the installation instructions include that information either
As for factory 69 390 with AC I don't currently have a build sheet with that combination. Only thing I can offer is that for 68 both factory AC and non AC 390 buildsheets show the same C8OE-B