Seen below is a picture of one of our trial slides in an application that needed the sideways motion on the stand to be prevented.  The accepted practice is to weld angle iron around the saddle to encapsulate it, but still allow movement in a transverse direction.

On our New Design we have thickened up the sides of the saddle. which allows us to then include 1/2" bolt holes to bolt the slide to the stand.  You don't need to do any welding, which reduces the inspection process and hot work permits.  Also a non-skilled labourer can then install these in the field.  All cost savings actions!

If you don't need them, you don't use them!