I bought what I believe is that same fitting and a drain cock for my compressor tank at the True Value hardware store. They had a very good selection of brass fittings and I think I paid $12 for both of them. The drain cock was about $8 as I recall...same size as the drain at the rear of the 235.

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end