Ok, I had a look at the various era Sideswipes I have here and here's what I've come up with:
- Japanese Diaclone Sideswipe: 1 verical line for each foot.
I think the Japanese Diaclone POLICE Sideswipe will have 1 vertical line, all reissues have 3 vertical lines.
At a guess I think the 2 lined ones are late pre-rub/early rub on Sideswipe and Red Alert? Maybe changed about the same time copyrights changed and the launchers for Swipe changed.
All the best- Maz