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Not that I can see it that well, but it looks like a multi splined bolt. I'd count the number of notches on it and see if one of the local auto parts stores has some like that. Probably 20 or more. I have a small set that MIGHT work on it that I got in the Kobalt tool section at Lowes. What I mean by small set is that there's 6 sockets in a 3/8" drive set-up. Kind of like the socket you need to remove the seat anchor bolts in an S series Saturn.
Stop by a Chevy dealer with your vin and ask them to generate a list of the vehicle as delivered. Should be able to back out either a GM part number or an aftermarket manufacturer, and possibly the tool that comes w with the set if purchased retail