Seat Pedestal question.
 

I have looked online for a replacement pedestal for my passenger side of my 182 Barchetta and am not 100% sure of the correct size.

I know it's a 2-7/8 diameter bit the length could be a 10 or 11. The 10" ones say they are 10-1/2 from the deck. So how can I have an 11" one? My tape measure says it's exactly 11" from the deck

Has anyone tried to pull the shaft out of this and replace it with other shafts? My 7" one is just too low.

For some reason I can't add a picture.