It would help to know the diameter of each - S, B, and C
What is the distance between A and C? (may not matter, but good to know)
I assume the bolts/studs/dowels in A and C are still in place?
The bores of A and C look smooth - can't see any female threads through A or C.
B does not appear threaded through, looking from the bottom. Threads could be smaller than the bottom OD. B could have a shoulder and splines, and be pressed in from the bottom. The male portion of B looks like it might be threaded. It needs to be cleaned and magnified.
It looks like the toolpost body is spinning freely on the compound. I assume B does not move when you rotate the toolpost?
What is the distance between A and C? (may not matter, but good to know)
I assume the bolts/studs/dowels in A and C are still in place?
The bores of A and C look smooth - can't see any female threads through A or C.
B does not appear threaded through, looking from the bottom. Threads could be smaller than the bottom OD. B could have a shoulder and splines, and be pressed in from the bottom. The male portion of B looks like it might be threaded. It needs to be cleaned and magnified.
It looks like the toolpost body is spinning freely on the compound. I assume B does not move when you rotate the toolpost?