I had to give it a name and “Overflow Tank Post” is ‘good nuff’. It forms the rear-most post for the Overflow Tank/Settling Tank assembly and also supports the framework at the front of the jig tank.
It only has one notch cut 1.250″ (nominal) from the top (5 ft FS) to receive the end of the Settling Tank Cap. Notice that I said it was `.250″ nominal from the top – in that it has to recevie the end of the Settling Tank Cap so the distance necessary to achive THAT is what is important in the end.
Explanation: In Secton I Part I the Settling Tank Posts were cut 2-15/16″ long. They were then dapped into the sill 0.042″ and into the Tank Caps the same amount.