turbo coolant line

[millertyme]

 <http://www.smileycentral.com/?partner=ZSzeb001> 
i have a '87 5KT and it has developed a weep at the coolant supply line
fitting on the top of the turbo.  i dont think i can get it apart,
without screwing the fitting.
does anyone know what the threads are inside the turbo for this?  i
checked with the dealer and the supply pipe is $143 and the fitting is
$64.  that seems like alot for a simple compression fitting.  i am
planning on making the new line out of thin walled stainless tubing, but
what to do about the union.  i have many different fittings for 3/8
compression type joints with pipe threads on the other end, but i cant
take mine apart until i know i can fix it with a cheaper (less
expensive) piece.
has anyone had this fitting out tell me what the thread is?
thanks
brian