I love the surf, so I'm on my third!
The first I had was a g reg 2.4 with bigger wheels and a body lift. it was a beast. Had it years,and always swore there was something wrong with it, but it just kept going no probs, and tough as old bots.
the second was a facelifted P reg 3l, very nice, but unexpectedly got a job in switzerland 1 week after buying it, so it had to go.
Now on an R reg new generation 3l diesel, but with intercooler :-)
The new (3rd) gen ones have things like a centre diff, ABS etc, not essential, but nice to have if you can stretch that far. You can pick up a 1996 one for circa 3-4k.
they didn't do a 2.5l diesel, assume you mean the 2.4l diesel.
Quite reliable, but with the 2.4, got to make sure the head is OK, they are a known weak spot.
3l is much better, with better power and pulling ability. Lots of info at hiluxsurf.co.uk
personally, i'd steer clear of the 2.4, unless you know the head has been properly changed.
There are some K, L and M reg ones badged 4Runner, which are UK cars, all Surfs are imports I think.