I could be wrong but...
I don't believe that Toyota made an extended cab with an 8' box in the older trucks. You either got an extended cab or an 8' box with a single cab. I think owners with the extended cab trucks got roof racks that allowed them to carry the longer stuff or used an extender with the tailgate down. Or you could have the bed extended...kinda like how people have their truck beds bobbed.
I've got a T100 standard cab with the 8' box that suits me fine. Not a lot of interior space fer stuff or a lot of power fer the 3.slow that's in it but then again...I don't carry a bunch of construction stuff around.
Did you need 4x4 capability? Auto or manual? Have you looked at the first gen Tundras? You could probably take one of the T100 extended cabs and mod that out with a V8 and extending the bed...guess it will depend on how soon you need it and what yer willing to pay fer it.
Diesel swaps aren't that prevalent...yet.