Thanks for the info Dave.  My brother went to the air/gas outfit today and ordered some Super 20 (ouch).  I believe they normally stock the 31 but they were out.  When they looked up the Rockwell hardness, they said they understood why we liked the Easyarc 620 - the guy said it was the hardest he had seen specs on.  I have some old charts somewhere - I'll see if I can find them.

Roger on the leveling device.  We have a bat wing mower that pulls duty as a rock/glass crusher behind the JD4430 - you think you have been shot.

Speaking of mis-named equipment, growing up we always wondered why it was not called the J.I. Case Rake Company, instead of the J.I. Case Plow Company.  I understand the neighbor kid burned the trash out of his dad's plow one time; I wouldn't give much for the plow after that.  The neighbor burned the tumble weeds out of his arena springtooth harrow just the other day; I wonder which cooled down first.  I don't want to be within hearing distance when he goes to use it again.