Automatic

An 04 is a 4.2.5 so the auto box should be fine. It was the early 4.2s that had a problem. The box should be quiet and the changes should be smooth. The kick down should be immediate. Make sure that the overdrive works properly (it is effectively the 4th gear of the box). It switches on and off with a button on the left side of the gear selector lever; your left thumb sits on it naturally when holding the lever. There is a tell-tale lamp in the dash just below the auto box gear indicator which illuminates when the overdrive is disengaged. Pushing the button in and out disengages and re-engages the o/d. It should operate smoothly and immediately; switching off the o/d is effectively changing down to third gear. The default setting for the o/d is “on”; it will always be on unless you switch it off, I don’t know why anyone would switch it off.
Obviously you need to check all the things that you would on any used car. You’ll already know that the 4.2 is a robust car but it will be just as susceptible to poor maintenance as any other car. As far as the auto box is concerned, Toyota don’t recommend any specific ATF changes other than saying that cars used in extreme conditions may need ATF changes. So you need to examine the service history and check that the ATF is at the right level on the auto box dipstick (you’ll find it at the front near side of the engine bay; it’s a red cap held down by a spring clip). Make sure it is reddish in color and doesn’t smell burnt; the coloir can be quite dark. For what it’s worth, we’ve had four 4.2 automatics since 2002 and never had to change the ATF.
Hope it works out well. Good luck 👍.