nelson bubble floor lamp

This nelson bubble floor lamp was given to me by someone who worked for Herman Miller for many years. The big puzzle about this piece is the base. Herman Miller says they don't recognize the number on the base (148).

I know that Herman Miller made special orders from time to time and I wonder if that is what the base could be. See I told ya it was a puzzle.

I would love to know anything that you big pool of expertise might know about the base. Year, maker etc.