I have a 95 4runner vzn130 V6 3lt and want to put a big fuel tank or sub tank on what is better and what should i do?

Is that the diesel model, and if so, are you outside the U.S.? The reason I ask is that one of the more common add-on tanks is a simple gravity-feed design, which is not approved by the USDOT (in a rollover, it is likely to leak fuel). The larger replacement tanks are pricey, but are probably a good choice for quality--the ones I keep finding are from Australia (Long Ranger and one other--you can find them with a quick web search for oversized replacement fuel tanks). There's also a thread on this forum, I believe under "Classic T4R's", where someone suggested using a Ford full-size pickup tank as an add-on. I have a 2nd Gen as well, and have been researching how to increase my backcountry range, too. Of course, there's always the fabricated route, using a local shop (if you have one that has experience with these--I wouldn't trust a first-timer). According to the ads, you will have to specify diesel or gas--not sure what the differences are (never had a diesel). Best of luck!