I'll ask at work tomorrow if I get time. I'm little busy at the moment. But I can't ask a mate who works in engine development who they use. Seeing as Jag and Land Rover are Ford owned we must use the same suppliers.

Used to use this link for my materials stuff http://www.gordonengland.co.uk/hardness/

Used to have some great conversion tables on there. I've dragged it out of my History so apologies if its no longer there