Short-T,
Here is the part:
http://www.docsblocks.com/products.asp?cat=20
Product ID: AC0146
Round Stock, Aluminum Refrigerant Valve 134A-standard flow Details
M10 x 1.25 Thrd switch port, .280 base
Price: $1.57
And you need a R134 schrader valve and -6 o-ring.
Here is a Pic of the whole rig including pressure transducer.
TR