BTW - I'm assuming that you have an Auto Tranny? spikedog asked as well... but really, it's all the same idea... most bang for the buck... and you have to ask yourself at what point does it make sense to quit spending money on something that never gets any newer :-)
as we all know though, the days of getting 15 years out of anything you buy today brand new are over, so old is gold, but with something like an explorer, there are lots of them out there, and people were giving them away when gas was over $4 a gallon here... I could have bought a 99 fully loaded for $2000, but it was a V8, and not the 4.6 the 5.0 - so it was really thirsty too... the 4.6 V8 would be a better choice, since many say that it is on par with some of the older 4L V6's...