GridMap & ShapeCast3D

Trying to utilise ShapeCast3D to detect the index of multiple GridMap cells it intersects with but I have no clue how to manipulate the collider data for that purpose.

Thought it would be more effective than a raycast since I'm trying to cover a boxes worth of cells & that the ray will stop checking even if it will hit a cell that is permittable - thus giving a false negative.

One collider result :

[{ "point": (0.0, 1.5, -8.0), "normal": (0.0, 1.0, 0.0), "rid": RID(3938485010434), "collider": GridMap:<GridMap#38537266680>, "collider_id": 38537266680, "shape": 13, "linear_velocity": (0.0, 0.0, 0.0) }, { "point": (-0.5, 1.4, -7.333333), "normal": (1.0, 0.0, 0.0), "rid": RID(3942779977731), "collider": GridMap:<GridMap#38537266680>, "collider_id": 38537266680, "shape": 4, "linear_velocity": (0.0, 0.0, 0.0) }]

I have tried identifying by getting the position of the collider but that returns the node & not the cell while rid is possibly not utilisable & I believe "point" refers to rotation - I have set the cells to occupy whole values only.