If the rod was worn from previous use,it can only get worse. I ended up using a piece of grade 5 3/8-16 rod. The nut size is 9/16. It took a decent amount of torque but I braced the tool in one hand and used a regular box wrench in the other. I oiled it and the washers just to help. With the block being so thick,there is a lot of thread there to hold strong and your rod is the weak link. I actually heat treated and quenched my block as well to keep the threads strong in there.
To be fair,my old bushings were so shot so the center pushed right out by hand. Then I scored the bushing race from the inside out with a sawzall. It came out no problem that way.
Schlag,I wrote your zip down and will get you a price. I'm going to guess it will be less than 20 or so. Putyoursoxon is coming down tommorow so we can install some headers on his M and we may do his bushes very soon after. Then you have dibs.
sent from my ATARI sc1224