The channel.
Where it meets the tree have it serrated (saw toothed) so it bites. Also have it just long enough for the mounting straps coz it's bloody heavy.
Where the lowering drum goes into the channel, welding alone I'm very suss on. Be great if it were bored and press fit in welded both sides, perhaps even a flange collar on the front to distribute the load across the channel. That would also prevent weekening from welding at the same place
