I did a post a while back and asked if there was a quick way to tell 1.5 Harland Sharps from 1.6's because they don't have any part numbers or sizes on them. I knew I could put them on a motor and wind it over with a dial indicator on the retainers, but that was a lot of trouble. Today I dug out the three sets I have and I know one set is 1.5's and one set is 1.6's and the other I didn't know. After I checked them, two sets 1.5 and one set 1.6, I noticed when you look at the up side down the 1.5 rockers have a recess to clear the push rods that is about a 1/4" long and the 1.6's has one about a 1" long. It is a big difference. I really need to learn how to do pics.

The push rod ajuster thats closest to the shaft is 1.6 ratio looking from the bottom of the rocker....Phill