You can fit the ARB bar for the 98-04 Tacoma. I've done it, but it does require the frame horns be modified just a bit. If you call ARB and ask for the tech department they'll give you the info you need on how it's done. As the 4runner was never exported to Aus they never built a bar specifically for it which is why it's not listed, but it is possible and not a particularly difficult job.
Marc