Getting old. Sold the ranch. Sold the tractors. Moved back to the city.
JD may have what you need. Check their website for parts.
Otherwise, I'd look for another B on eBay or Craigslist.
I bought two Minneapolis Moline P3-6 drills (10 ft wide, 20 drops, grass seed boxes included) from a neighbor ($275) and used parts from both to make one good drill. Your B is similar to my MM.