Ok, had a look for a 12mm bore, hubless, mod1.5 steel gear. Came up with this:
https://sdp-si.com/eStore/PartDetail...70&GroupID=591
Here is the pdf info on the gear familar, just look at the 36t hubless info in the 1st table.
https://sdp-si.com/eStore/..%5Css%5CPDF%5C78501072.pdf
At 22 bucks plus shipping it is not too bad. Diameter is 57mm on the 36t gear, so not sure if it is too big to fit with the stock center bulkheads...
If those links do not work, search sdp si on google, and put this part number in their search feature: A 1C 1MYK15036