Hi Raj,
The thing about extruders is that the mounting holes are not determined by the design, but by the person generating the STL file from OpenSCAD source code.
You see, most design out there are "parametric", meaning there are a few details you can fiddle with before you generate the STL file. Mounting hole size is one of those parameters. If you need some help generating an STL with your requirements, ask for help.
Here are some links
OpenSCAD
Greg's Accesible Wades Extruder v3 is a more robust design of Wade's, and it's parametric, which the original Wade's is not.