I did a very low cost expansion to my 54" John Deere grader blade. It is now 72" wide.
I used some scrap rubber stall mat for the extensions. The pieces were 12" wide X 18" tall.
I used some scrap 1/2" galvanized pipe for the back braces & pieces from each end of a worn out cutting edge from a 54" blade for the front cutting edge braces.
The 1" X 4" X 72" rubber cutting edge was a cut off from another blade.
The extensions seem to be very strong.
They are calling for snow over night, so I might get to try it out tomorrow.