models -> spore_endstone_block.json

{
    "credit": "Made with Blockbench",
    "textures": {
        "0": "contenttweaker:blocks/spore_endstone_up",
        "1": "contenttweaker:blocks/spore_endstone_side",
        "2": "blocks/end_stone"
    },
    "elements": [
        {
            "from": [0, 0, 0],
            "to": [16, 16, 16],
            "faces": {
                "north": {"uv": [0, 0, 16, 16], "texture": "#1"},
                "east": {"uv": [0, 0, 16, 16], "texture": "#1"},
                "south": {"uv": [0, 0, 16, 16], "texture": "#1"},
                "west": {"uv": [0, 0, 16, 16], "texture": "#1"},
                "up": {"uv": [0, 0, 16, 16], "texture": "#0"},
                "down": {"uv": [0, 0, 16, 16], "texture": "#2"}
            }
        }
    ]
}