It goes on the right side of the firewall and will only fit in one and only one place. Place it there and drill the many rivet holes required and rivet it on. Use flush rivets with the heads on the firewall side, if you are not mounting anything else there machine the bracket and put the rivet heads on the inside. If you put the heads on the fire wall side either dimple the firewall and machine the bracket or lightly machine the firewall and use NAS rivets to hold the bracket on with.
NAS rivets=oops rivets. I use them for all my nut plates etc saves a lot of dimpling etc.
