Leyland Super Hippos

It would seem everyone had their own designation system but your 680T does sound like the turbo'd 680.
Some power figures would soon tell.
As Ergo Mike noted, the 690 (680 turbo) had engine modifications but was basically the 680 cu in engine.
Gudgeon pin oil spray to cool underside of pistons, larger inlet valves, hydraulic governor on the larger deliver pump, bigger injector nozzles with higher crack pressure and so on.
This old girl (courtesy Dave from WA) was delivered with the left hand version of the turbo 680, R/R box and single point Leyland arse end.
Dave relates it was a dreadful engine and when it's days ended was replaced with a 220 Cummins making a decent truck out of it.

Where were those Chevies goin Jeffo

Can't help you there. So long ago I doubt Dave would remember either.
Bet it's to do with oil/gas exploration, gold mining etc up the top left of W.A.

Here are pics of the dog trailers mentioned a few posts back.
3 views of one of 2 ex Marion Downs/NAPCo dog trailers I located in the Clermont Area of CQ. As can be seen

Oldfulla, Peter thank for those photos, the trailer look longer than I thought they were, they must be around 25 to 30 ft, it be good if this bloke can get it all together for the Alice shindig, when I meet one of the original drivers back in 2010 on the way home from Alice at Boulia[spent 3 day with him and meet up with him a couple of times since] He was so passionate about his time out there that when we travelled with him between Boulia Qld and Winton Qld we stoped at all the places where they used to stop at to eat, only ruins or nothing left at these places. The man in question is in one of the earlier photos, the one with sunglasses on in the photo the truck and the drivers in.
Colin

Colin

They are 28 footers. the first few they had built were with single axles both ends. They were no good in the sand - so were sent back and converted to tandems.

Oldfulla

gday all .in pt hedland not long ago and saw this old Leyland in the park / out door museum looking a bit sad.





the info sign was gone, but all the other gear there was used in the minning exploration and railway work. cheers robbo

G'day Gentlmen

Leyland at Pt Headland was a Manganese carting Truck from Woody Woody mine {out the back of Nullagine}
Don Rhodes {of Rhodes Ridley Fame} Built the trailers --mined and carted the Manganese to Pt Headland for Export

Oldbob 70

Been meaning to post this sad relic for some time, think I found it parked in the Gulgong Museum, and well worth a visit.

That's a really early post war one, isn't it? I hope someone restores it, not many are left.

The below is in Israel at a collector's place and is safe for the time being, but restoring old trucks over there is difficult because of their stupid registration rules, which may or may not change in the future to allow driving old trucks on collectors plates.