Bartamos posted good advice.
Here is how I obtained all the hoses for my 54/55 GMC 350 (vacuum for hydrovac, and vacuum for speedometer-2-speed-ratio-selector, and vacuum for 2-speed rear-end selector, and oil filter lines):
I found a northeast company,
Omni Services, and they tried to match all my hoses, but most/all the fittings were odd.
The manager said he would make "new" hoses from my fittings: cut and then weld the threaded-end to a new barb hose fitting (silver soldered I think). The cost was incredibly low (around $15 for each hose, including the two new barb-hose fittings).
