I appreciate everyone's help. I think the matter is now resolved, but a couple of interesting twists. First, the steering knuckles I already had were apparently not the wrong ones after all. When I inserted the balljoint, it would not seat firmly - there was movement and it could be rocked slightly by hand. Now I have a second set of knuckles, same size as the first, and the ball joint fits as snug as can be. The problem with the original set? I'm guessing that after 40 years of wear, the tapered hole was either out of round, or no longer straight. Any other thoughts? The second point of note is the effectiveness of this site. I send my query out, it goes all around the world, and the fellow who replies lives less than 4 km from me. I never knew "240dkw" (Dan) who is perhaps the only other guy in Red Deer, Alberta (pop. 90,000) with a stripped-bare 240 in his garage. He contacted me, and offered me his already-sandblasted steering knuckles that will likely end up on my car. Thanks Dan, and thanks to the people who developed this forum.