Damper retaining bolt?

Yes, confused me too when I noticed no crank bolt in my 1964 slant, but apparently how the factory shipped them. My guess is they used a hydraulic press to push the damper on, perhaps threaded into the crank snout, then removed the tool. I vaguely recall turning over the engine in my 1969 Dart slant using the crank bolt, but perhaps added by a prior owner. I found no crank bolt in my 2002 Chrysler 3.8L V-6, but only because some gomer had sheared it off and left the remainder recessed in the crank snout. In one of my wins, I was able to drill a perfectly centered hole (used a sleeve on pilot drill bit, and a new carbide bit), then enlarged for my largest Easy-out (actually worked for once). Anyway, the damper was stuck tight on that engine without a crank bolt.