The oldest designs went through the most changes - this was before we started to use version I, II, III designations for major revisions. This applies to Original S.E.X., AfterGlow, eXcite, B-Glow, and to a lesser extent the parafeed amps ParaSEX, ParaGlow, and ParaBee.
I started to write down some of the changes I remembered, but the post got hopelessly complicated as I kept remembering more changes and revisions. Suffice it to say that, when considering changes to any of these older products, you may have to do some sleuthing to uncover the exact configuration!