I have found that the depth of the case between the 99 and the 128 is different. I have a cabinet that you can drop one into, and it needs a spacer for the shorter base.
Singer made tables for both the full size and 3/4 size bases, along with the FW and the 301 and 401 sizes. They are all different.
This particular base should have a hole for the knee controller, however the table probably was not made for a machine base with that set up, as it's quite a bit newer. My cabinet is set up for a machine with a knee controller, however it takes a special knee bar as the one that works with the portable base does not fit.