Guys
Jet & Prop issue 2/2003 had an article about this.
I take it that neither you Paul or Doug has that article?
If you send me
hagel.jarlevik@bredband.net your e-mails I will scan the article for you. Basically it seems to confirm what Doug is saying, but gives a lot more schools depending on the letter after the cross.
Cheers
Stig