Chevy cargo van prewired for speakers?

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If I have asked this question here before, I apologize as I haven't found it....

Is a 2005 Chevy cargo van prewired for speakers in the rear? Mine has 2 front door speakers only. I've searched but the best info I've found is from Crutchfield:

2005 Chevrolet Express van w/o Onstar

Front speakers
Front Door: 6-3/4"

Far Rear speakers
Tail Doors: 6x9"
Rear Roof: 4" Your factory speaker doesn’t match any aftermarket speaker size exactly. Here, we list the largest speaker that will fit in the factory location. As you shop, we’ll show you all options for this location.

I've had the panels off and nothing jumped out at me as potential connections but this van was partially customized before and I wasn't looking for audio connections at that time. There was one half of black harness connector wired in at the top-center of the rear doors that I noted but didn't test. Just wondering if anyone has first-hand experience of what I should be looking for?

I'm not looking to get ridiculous but thought a pair of good 6x9's would be nice if installing them would be easy. If anyone has any pics or sources for information about the wiring or physical factory locations, I would appreciate it!

Thanks!