They did so use one. Not common, in fact I don't remember seeing one on any early slant, but, in the later part for the '70's and later, lots of trucks had them. Mostly manual trans applications and engines with the multigroove balancer.
Ok. I'll it this way. "I" have seen and worked on a LOT of slant sixes in the forty plus years I've been workin on cars and "I" have never run across one that had a crank bolt in it. That includes the lots of them I've seen in junkyards and everywhere else. So the vast majority "I" have seen did not come with them.
