Did it cure the knock on your old ZS ICE successfully by replacing the whole steering column ?.
The knocking noise appears to be travelling "UP" from the lower end of the steering column assembly.
The firmly believe that the knocking noise will be being omitted from either, one or both of the UJ joints.
The upper steering column shaft, is generally supported at each end by a fairly simple plastic type top and bottom bush arrangement.
The UJ joints are located at a very lower end of the steering column.
This double ended UJ joint, enables the mechanical transition between the end of the steering column and into the entry point of the steering rack.
The angle required between both steering components, is very steep and offset.
This therefore necessitates the need of two UJ joints to overcome the difficult connection angle of both items.
This type of UJ joint system has been widely used on cars over the years.
What is very uncommon, is to witness a failure like this so early in the cars life span.