I have a 99 model GXL Prado manual V6 Petrol which are the same release as the 96-99 models you are looking at. I cant fault the car at all. We make sure it is always serviced on time and what needs to be done is done at the time and not put off until the next service, but its just about to clock up 300,000kms and has never had a problem. Just make sure you buy one that has been looked after with servicing and not bush bashed.
I bought mine from a mechanic who had it for his wife and kids. With no bullbar, no towbar, roof racks etc and spotless underneath I knew I was buying a mum's taxi and shopping trolley and not a car that had been flogged up and down rocks, drowned in salt water or up to its bonnet in mud. Approaching 300,000kms it doesnt drop or burn any oil and has never let me down ever.
I found the fuel economy when I bought it extremely good for such a large vehicle running on petrol, and found it comparable in consumption to our 2003 Commodore wagon. Since adding a big heavy bullbar, towbar and heavy ARB roof rack the economy has slipped a little but never worse than around 16L/100km.
I live out west and you would be surprised how many Prados are getting around out this way, they have really given the Landcruiser GXLs a run for their money in popularity and personally I think they look better too.