Differential Screw source??

Before I try to make one has anyone a clue as to who may stock 'differential screws'?
The one I need is 21mm overall length, with 8mm standard right hand thread
at one end, and 8mm left hand thread at the other, this end having a 4mm hex socket recessed into it like a grub screw would have. It's in high tensile steel and used for tool clamping in a indexing hydraulic tool post on a cnc lathe.
Any pointers appreciated before I go and buy an 8mm lh die!
AWEM
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http://www.shop-apt.co.uk/clamp-lever-screws.html
its a start, maybe they can help with the exact size
--
mick



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"mick" wrote in message

--

Mick,

Excellent - many thanks - strangely I seem to already have an account with
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