As I discussed earlier, the directions for installing this vise strongly urge you to follow them exactly and precisely. Suitably intimidated, I began by drilling the 1 1/2" holes in the front and rear jaws, which in my case are 26"x7". Be aware that the minimum jaw depth is the thickness of your bench top plus 4 1/8", which will give you a throat depth of the thickness of your bench top plus 1". I made my jaws deeper than the minimum so I could have a little more than 3" of clearance.
The screws can be a maximum of 16 7/8" apart on center for the standard vise, which seemed fine for my 26" wide bench. This is where I dodged a bullet. The vise screws ended up clearing the insides of the 4" thick legs of my bench by 1/16"! "What do you not understand about the term 'on center'?" I muttered to myself when I realized what had happened. My point in revealing this lapse is that you should be more careful than I was in determining clearances unless you can depend on being similarly lucky and that you may not be able to get the full width between the screws if you mount it as an end vise, depending on the width of your bench and the thickness and location of its legs.
Great emphasis is placed on making sure that the holes for the screws are precisely aligned and parallel through careful use of a drill press. I added the extra precaution of using double stick tape to make sure that the jaws didn't move relative to one another as I drilled through both at once.