Did some further searching and found this thread:
www.peachparts.com/shopforum/diesel-discussion/238488-backyard-speedometer-adjustment.html

Explains what I have to do - I’ll see if I can get it figured out. I don’t care about perfect accuracy but within 5% should be fine.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k