Dear Steve. How does one break a trunnion? If it is broken try a small machine shop and have them braze the cast iron (assumption for 1983) or if they are real good they can arc with cast-iron rods, if this is a machine you purchased in parts, have them make a couple of 1/2 moon brackets (check cost) and if it is to much put it back on craigslist and look at the new Grizzleys - much better quality than before and sale prices are great. Lastly, look at the manuals from Jet, Delta and Sears from the same period find the one with the closest design, epoxy wood blocks to the back side of the table and screw the different trunnions in place, after squaring the whole conglomeration.
There is always a solution, whether it is cost effective or not is a different issue
Good luck - Baker