Definitely looks DIY to me. And it doesn't look like the end of the bottom bolt, at the head of the bolt, is supported. If so, I wonder if the mount is flexing and causing some misalignment or loss of belt tension resulting in the squeal.
At the very least, I would dump that and find either a non-AC bracket or cut down an AC one. Note that an AC one won't work with the truck PS mount if there is no pulley at the AC location. Not sure if you currently have PS or not, just don't want you to get fooled if you do and don't end up deleting it.
