Taken from
http://www.AmazonHose.com7032x is what you're looking for. 1/2" NPT female to female union. Mine was round (no hex in the center) and 316 stainless steel, but that's a generalized picture. Cost was $3.80. Since they're local, I had them cut the union in half, giving me two bungs essentially.
Then:The part there is C5205x, tube to male fitting. They sell that in -10AN to 1/2" NPT. Aluminum was $4.80 each, and the 316 stainless was $12.85 each.
They have 4 locations in FL and one in Chicago, but an online catalog, so I assume you can call up and ask for these specific parts and they'll ship them. -Jeff