Thanks.
I forgot to mention, it's a 59 3200.
I'm pretty sure that mine has the type with the "bolt", I guess kind of like a banjo bolt? And that is the part I've lost.
The block has one threaded hole on each end, and one larger, threadless hole in the middle, all the way through.
Is there any functional reason why I shouldn't just go to the parts store and find a block that will join the two hard lines and the hose, and just forget about trying to find this piece?