Today, Jim and I installed the 4 vibration absorbers on the EY PCAL Periscope. Since we only had the one type of D1600401, we had to mount them on the 45deg spokes as shown in D1200174 on the last page. See attached pictures, though kind of hard to get good shots due to access.
One issue we ran into is that the vibration absorber assembly drawing (D1002424) says to use 1/2" long 1/4-20s with a washer to mount D100895 to D1600401. We found that the screw would still poke out the back even with a thicker washer. We had to double or triple washer stacks to keep them from protruding.
I forgot to mention that we mounted the vibration absorbers on the 3rd and 5th spoke holes, counting from the inside.
Also, looking at the drawings for D1600401 and D1000895, there should be 0.54" of material for the screw to go through. With a washer on as well I am very surprised that we had any issues. The bag of screws we used was labeled as 1/2" long, and I did a quick look on a ruler to confirm, but perhaps they were really 9/16".