[SSJup81]

Some of these older series you're probably curious of can more than likely be purchased now or rented, due to its being licensed, so finding fansubs of such things would more than likely be tough since they have official dub releases. Some of these series have dub audio as well as original Japanese audio with subtitles. Some just have a dub release, but seems that most have it so that you have both options to choose from.

Yoroiden Samurai Troopers (Ronin Warriors) come to mind. It's an earlier series (technically 80s), but a few years ago, Bandai released the boxset of it (out of print now). It has both dub and subs on the DVD, as well as the OVAs that came out for the series.

I have both Gundam Wing boxsets, and that's from the mid-90s, technically. The option to go with either Japanese audio + English subtitles or dubbed English audio is there.

I'm pretty sure series like The Slayers (90s) also have an official release with both sub and dub option. Oh wait, of course it does. I just remembered that the sub of The Slayers and Slayers Next used to air on the International Channel back in the early 2000s. I don't recall if it ever got around to showing the series after Next.

Anywho, what "older series" are you interested in aside from Dragon Ball (which I think has a dub/sub release) and GTO (I think this does too)? I'm actually curious.