I expect that the 260E, being the economy version is typically bought by those not as interested or desirous of performance. If that is their desire, then they are probably much lighter on the loud pedal.

Just a theory, because I can't imagine anything else that could possibly explain it, it also seems to fit because the most important factors in engine life is the preventive maintenance it receives and how it is driven.

My 300E is sitting at 268,000 right now and is in exactly the same condition as the 260E in the original post. I see nothing in sight that will have it in any different condition a hundred thousand miles from now.

IMHO the M103 engine was ahead of its time. Most all brand engines designed in the last 10 years or so have gotten to a point where oil usage and other ill behavior of the engine mechanicals are a thing of the past. These new engines just don't use oil and last a long time if cared for.

I realize the problem with the valve stem seals, but at least it was something easily fixed without tearing everything apart. The engine from the deck down is just bulletproof.

Couple these great mechanicals with fuel injection, which is probably more responsible for the long engine life than the mechanicals themselves, and you have an engine that is as long lived as a 123 diesel.

Have a great day,