Size of Crankshaft pulley bolt?

I pulled my engine on Saturday.  It was still running on three cylinders and
I took the car on one last drive beforehand.  I expect it to be laid up
until Summer.  Needs a full engine rebuild and a Datsun tranny transplant.
What size of socket do I need to get the Crankshaft pulley bolt off of my
1275?  I'd rather use my impact wrench than a hammer and chisel :)

Curt Onstott - Crop and Soil Science Computing Admin 
  Oregon State University. - (541) 737-5875 - Office: CrpS 153b
                    http://www.css.orst.edu/curt
No, life IS a contest.  Perhaps it doesn't FEEL like a contest to YOU
                because I WON so long ago.  -Voorhis
  '70 MG Midget    '75 Jaguar XJ6     '95 Specialized RockHopper