The Spunding Valve assembly is as follows, going from left to right and then up and down.

-modified stainless tailpiece
-Micromatic wingnut
-1/4" NPT Hex Nipple (McMaster #48805K81)
-1/4" NPT Cross (McMaster #4464K312)
-1/4" NPT x 1/8" NPT Hex Nipple (McMaster #48805K86)
-Back Pressure Relief Valve (McMaster #99045K46)
-1/4" NPT Gauge from Ebay
-1/4" NPT Male x Female 90º Elbow (McMaster #4464K36)
-1/4" NPT valve from Ebay
-1/4" NPT x 3/8" ID tube barbed adapter (McMaster #5670K85)

The 24" Thermowell is from Brewers Hardware.
Sealing the Thermowell is a 1/4" NPT x 3/8" OD tube compression fitting (McMaster #8239K22) which is threaded into another modified stainless tail piece. The o-ring that seals the thermowell to the compression tube fitting is McMaster #5233T52. The compression fitting had to be modified by drilling it through to a 25/64" ID. The Shut-off Valve is from Micromatic.

The modified tail pieces were made from a 5/16" Micromatic unit. The barbed section was cut-off, then the base was drilled out to 7/16", then tapped with a 1/4-18 NPT pipe tap.

The racking tube that goes in place of the thermowell for transfers is McMaster #9797T142

The original keg stem has the ball and spring removed and the stem is cut off just passed the indents for the spring.

Thanks so much for the parts list- I am going to make me one of these!

There's a thread over at Home Brew Talk about pressure fermenting.

Just one quick question- after studying the image, is the coupler a standard "D" to fit a normal US keg? It just looks a little different an d the threads / hookup might be different.
thanks,
Gary

It is a standard D coupler from Micromatic with the check ball and retainer and the check valve removed.

"The racking tube that goes in place of the thermowell for transfers is McMaster #99045K46" this is the same part number as the pressure valve. Also are any of the parts multiple units besides the tailpieces? If you have picts of the racking cane assembled it would help. thanks again, Gary

just noticed this- is there a threaded union that screws to the top of the D coupler to connect to the wing nut /thermowell? Didn't see it on the list.

I corrected the typo.
Other multiples are the wing nuts and the washers for them. I use silicone orings from McMaster, #9396K209, instead of the black rubber washers that are standard. That threaded union you mention is the micromatic shut off valve.