I looked for one. 3/16 1/8 3/16 reducing T. McMaster was a wash. Autoparts stores were a wash for metal, but they do have a plastic vacuum T in the over priced "HELP" line of parts. I used it last time, and it broke upon disassembly. I was also never completely convinced it was gasoline safe. There was a plated brass one on eBay, but it was 24.50 plus tax, and the 1/8 leg had no barb. I even looked for an OEM part on the manufacturer's parts page, but was not able to find a parts breakdown that included this part.
This was my answer.
