I read that in the 1980's the w123 diesel was the most common taxi in the world. I think that is a good indicator of the 61x motor..
I have a 300d parts car that I did 800k miles before I replaced it. I have seen one that had done 1,500k miles, without a rebuild. I guess that it helps that these cars would normally do at least 100 miles every time the key was turned, no short trips!
We only use proper diesel so many of the coking and injector problems dont happen.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving