I researched this question about 10 years ago. forgive me if my memory is faulty.
At the time, I phoned the Roads and Traffic Authority of NSW, and was advised that 39 6.9's were then currently registered in NSW. I also rang MB Australia in Melbourne, who advised that 280 6.9's in total for all years had been imported by them into Australia. By implication, they would all have been Australian spec. cars. The 1979 model year is by far the most common.
I still have a record of this inquiry buried deeply somewhere in my notes and records of my own car.
Quote: "The best laid plans of mice and men are filed away .............somewhere ........?"
I know of a few private import 6.9's which are all right hand drive. Again, by implication, they would all have been English spec. cars. These cars have come from many different countries to be privately imported into Australia. I estimate that up to 50 of these cars were imported. Some cars of all spec.s may also have been exported in this period, but I don't know of any.
I have personally driven seven examples of the 6.9
The 6.9 is a long lived car for two reasons:
1) Being top of the range for the W116, more owners are enthusiastic to keep them going, partly because of the suspension and engine, and
2) The car was overdesigned in many ways, I think specifically to give it a long life.
I know of one write off 6.9 (English spec.) and three 6.9's Australian spec. that have been dismantled, to be parted out.
At the time, I estimated that the survival rate of the 6.9 at 20 years of age was about 50% and there would been about 100 6.9's in current registration in Australia, ready to drive. I don't think that number has gotten much smaller in the following 10 years to present. There would be quite a few more that would be unroadworthy.
As far as specification is concerned, the Australian cars had extra side impact protection in the doors, a gearbox cooler pump and an auto gearbox which is different to the English / German cars, with 4 clutch plates and a 10mm shorter gearbox case. They also had the low 8.0 to 1 compression engine and an air pump for air pollution control. The Australian cars can be easily identified by the extra pulley for the gearbox cooler pump just behind the radiator, unless that has been removed. MB in their wisdom installed the gearbox cooler pump because of the higher ambient temperatures in Australia, and considered that the Australian cars would be more likely to pull a trailer occasionally.
The English / German spec, cars had the high compression engine, seven plate clutch gearbox, and a small separate vertical oil cooler radiator alongside the main one.
The Australian spec. cars produced 269 horsepower, not 286 h.p. and 510 mkg torque, not 560 mkg torque.
Most of this is from memory, and I guess that Styria may be be able to correct me on some of the technical details
