fuel consumption

Why don't you look in the fuel consumption sub-section of the 'Trip Planning' section on this site. I believe I'm the only one giving fuel consumption figures for the chevy 6.5ltr V8 diesel. The best consumption I have managed over 70,000 km is 7.4km/ltr & average around 6.5km/ltr on trips. I have high speed diffs fitted to my Troopy which keeps the cruising revs down to 2000rpm @ 100km/hr. Cheers.

While I know it is a different vehicle I went from a 4.2 (1hz troopy) to the Humvee with a 6.2 V8 diesel, both weigh similar amounts and fuel consumption is about the same (never more than a litre or so per100k) on the highway.
Off road the Humvee will occasionally use a tad more especially if you sink the welly in sand and travel much faster than the troopy could ever go.
A friend with a 6.5 in an ex3F petrol 80 series uses anything up to half the fuel that it used with the petrol six.

If it's any help, I did a 6.2 litre swap into my 75 series tray, from a 6.6 litre petrol. The diesel was very consistant, around 14 to 14.5 litres per 100kms., whether loaded or not, if never varied by more than 1 litre per 100km. However, it blew up, I could get a replacement quickly enough, so I dropped in a 1HD-T, which was a far superior engine in almost all situations and it's consumption was 12 lts/100.