Okay then, my 2c:
I notice bellbirdweb says he gets 23L/100 in the HDFTE 100 series towing full height van.
I get 25L/100 towing 18.57-6 in my PETROL 200 series @100km/hr.
200 series petrol are newer, cheaper, more comfortable, more capable off road and have more safety and luxury features than TD 100 series. crawl control and KDSS standard on all petrols. Yes, they cost more in fuel, but much less for servicing. ULP is 10-15% cheaper in cities too.
You get the V8 note and arguably one of the most reliable vehicles on the road.
If you do moderate annual kilometres (I do about 10,000 plus trips), you could crunch your numbers and I'll reckon you'll come out in front. If you do lots of kms or lots of towing, you wont.
We have the 76 wagons at work and I hate them. Noisy, slow, uncomfortable, horrid (manual only) gearbox and you'd be safer and more comfortable on a moped. I seriously believe that if they were a 6cyl, Toyota would have sold 0 of these.
Now that's just my opinion and everyones different, but there you go