Hi Maurits,
I have a rhd 1968 280SE automatic as well, but it has steering-column
gear change, with the gear indicator in the instrument cluster. I
don't own the 280SE 3.5 in the picture I used, just used it to make
the point that in the 1960's MB seemed to engineer everything up to a
standard rather than down to a price. Incidentally, a few years back I
dismantled a 50k-mile rusted 1971 280SE for its salvage parts, and I
was amazed at how many differences there were between 1968 and 1971 on
basically the same W108 model. Obviously the oil crisis forced a big
re-think about building heavy thirsty cars. For example, on the 1968
car, all the seat fixtures were made of solid metal with chrome-on-
metal trims. By 1971, all that was chromed plastic.
Your 1968 280SE might have the older fluid-coupling transmission that
changes gear with a thump? The MB manual says the later torque
converter-type transmission can't be fitted. I have done it
successfully ;-), I didn't get the factory manual until a few years
after I had done the job, and I'm no a pro mechanic, just a self-
taught enthusiast. If I had read the manual first, I wouldn't have
attempted the conversion.

the W108's are still my favourite MB's, along with the Unimog 404.

John