I know for a fact that at least one 69 340 (mine) got them. OK, seriously, I had them put in mine about 25 years ago because everybody said I had to. Although now I wonder if it is really that necessary. I talk to people all the time who say they did not and have no problems. Modern fuel is better and cleaner than it used to be. I wonder if that helps offset the lack of lead. Remember how dirty and crusty valves and combustion chambers used to be when disassembling an engine? I pulled the heads off my 340 a few years ago to replace a leaky head gasket, and everything was as clean as a whistle. Hmm, exactly how clean is a whistle?