my two cents

My guess is that they most likely had the English translation, and the adaptation possibly, as well as the english soundtrack for an international audience. They most likely never dubbed the whole series as these shows during that time were never popular in the US. It most likely met the same fate as Candy Candy. It's most likely the distributers that distributed the show outside the US (especially in LA countries) sent out the official English translation that went along with Ziv's editing/mastering. They might have made the editing and all, but probably never dubbed it. If anyone wanted to find out if there is an English dub for later episode, though, it would be wise to contact someone who worked on the international dubs that featured the English soundtrack (i.e Mexican voice actresses, dubbing directors etc)

Btw you can actually hear the English intro being played in the background in the Spanish dub: http://www.dailymotion.com/video/x5t52bg