Finally found out!
After 2-1/2 days of deafening silence on this board, I took matters into my own hands. It looked like the threads were about 15-16mm, but the pitch didn't make sense (about 0.8/mm). So I drug the box into my local True Value hardware store & headed for the plumbing department. The threads don't taper I.e. not NPT), so I rummaged around in the brass compression drawers & found that a 3/8 male fits perfectly.
So for all those other SBC conversion folks out there, you don't have to pay Downey for the magic lines. Any heavy equipment outfit can make up lines to your spec. For those in the front range Colorado area, the best place I've found is Struble Fluid Power. They've mailed me stuff in Castle Rock, so I'm sure they would do it anywhere UPS or FedEx goes. They stock the industrial Earl's stainless teflon that's 1/2 the price of the racing stuff.
