May I ask: what was different? This is the first time I’ve heard of this and I’ve only seen what was, likely, the new edition.
Parts V and VI were removed from the wife's version.
1. Letters That Produced Miraculous Results - cut because correspondence norms had massively changed between 1936 and 1981
2. Seven Rules for Making Your Home Life Happier - cut because its 1930s-era perspectives on marriage and domestic life didn't age that well
Personally, I think some of the edits in the remaining sections are more controversial than the removal of those two sections. I think the revision lost quite a bit of Dale's charm and just felt a bit less idiosyncratic in a bad way.