In response to the guys about the 1KZT-E Motor. I have one in my landcruiser prado which I have in florida, but that's another story. Have had the truck in the family for the last 20 ish years.
Mainteanance - Oil filters and regular diesel engine oil. Filters can be ordered online or through your local dealership with a part number. I have over 220k miles on my motor - with stock injectors, glow plugs, ect. Fuel filters should be changed every few years and can be shipped from the UK. These things are cheap to maintain. MPG- I average 20 around town, 22 on the highway, but remember the prado is a tad heavier than a 4runner, and I tend to cruise around 80-90. - 33" tires - lifted. Stock these fetch 25mpg easily.*
I've driven the 3.4 Lump. Good motor, but you really need to rev it as the powers up high. I tow a lot, 2-3 tons, and the diesels low end torque is no match for the petrol engine. Both great engines, but with the efficiency of a diesel motor and cheap/low maintenance it's a easy win in my OPINION which is the better engine. In Europe ,Australia, Africa ect where markets were given the choice of both petrol and diesel versions, most markets sold many many times more diesels over Petrol models. Ask yourself why,*
Just my two cents.*