Help with baseband upgrade?

I want to install CM13 on my M8, but before I do, I need to upgrade to mm baseband. I'm not sure which version to download, though since my m8 is att I assume GPE would be compatible, since they are both gsm. following the link in this thread did not work, Dead link.

http://ift.tt/1WS3kfF

Can anyone tell me if gpe baseband will be compatible, and link to a download for me?

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