Halo 3 GPD modding?

Hi, I have a question. Are there any working Halo 3 GPD modding tools within Horizon? Or maybe any external tools? I’m trying to edit it to give myself legendary completion, skulls, and maybe to mess with my armor.

The tool named Halo 3 GPD Editor gives me this error

Horizon only has a save editor for Halo 3 allowing you to edit your ammo.

Are you sure you’re trying to open the correct GPD file in that Halo 3 GPD Modder?