no locking nut on the m110. i invested in the crowfoot here:
http://www.samstagsales.com/images/hz2768-1.jpg. made the job super easy and quick. i viewed it as necessary as valve adjustments on the m110 are supposed to be every 12,500 miles. there is a lot of resistance when adjusting. i use a 1/2 inch breaker bar to make it a bit easier.