Yes, the adjusters span several years of production. The adjuster thread is 7/16-20, and jam nuts for them are available in bulk on Ebay. Check the Smith Brothers company website "pushrods.net" for a source for new adjusters. I bought several of them there recently. It is a very simple job to fabricate pushrods from stainless steel tubing that is stronger and more durable than the original part by simply cutting the ends off any stovebolt pushrod, regardless of length, and pressing those ends into the tubing. There is no reason whatsoever to pay the outrageous prices the resto-ripoff places want for scarce parts such as those pushrods. Send me a PM for a more specific conversation about the procedure if you like. I made my own pushrods for racing engines for many years, ones that ran at several times the speed and power output of a stovebolt six.
Here's enough tubing to make six pushrods:
https://www.ebay.com/itm/334006272037?Jerry
