ouch.
looks like 20.5 on the indicator, which for a '78 617.950 means 9 degrees of stretch. man, I should have checked this sooner.
this is on the engine which I pulled from a '78 300SD to put in my '67 chevy pickup. the odometer had stopped working on the 300SD at 278k miles, and I've been driving it for about 2 years now, so I'm guessing its over 300k by now.