If you are going to install the Ray Allen Flap Position Sensor (Section 54) or even if you are not sure that you will, drill the hole in WD-1013A called out in 54-02, Step 3 while you are installing that crank in Section Page 34-04.
The amount of effort to drill that hole after the crank is installed is significant, or you can remove the crank, drill the hole and reinstall it. Even if you do not use that hole you are better off doing it at 34-04.
UPDATE 9/9/17:
I say again,
SIGNIFICANT effort to remove the crank WD-1013A after it is installed. The note to refer to 34-04 for un-installing it is that you undo what it told you to do there. It is now a bit more difficult because there are a few more things in the way, etc. I originally did drill a hole in the crank with a right angle air drive drill - that wasn't significantly difficult, it was close to impossible! You have so little clearance that I had to cut off and shorten a drill at both ends so that there was enough untwisted shank to grip in the chuck and then re-point the dill bit cutting end. There was enough drill bit length then to get into the close quarters between the crank and the under-floor rib. You can't center punch the drill location; it's hard enough just to see it. I did my best to measure for the location of the hole and get it in the right place. But, the crank is powder coated which makes it 'slippery', it ended up walking a little and off by about 3/32". Plus it hard steel and I had to resharpen the bit twice.The whole process to drill that hole while the crank is in-place was VERY difficult. In all, it took about 3 hours+, and not in the right place.
Now I am removing the crank per the instructions and going through a whole new series of tight quarter body contortion and leg cramps. I feel that I need to get the hole in the right place and I have enough room to do that that is far enough from the first hole. And, I will have to reinstall the crank in those same close quarters.
The easiest thing to do if you have not installed the flap crank is to go ahead and drill that little hole that needs to be in there BEFORE you do install it. I hope that Van's revises the instructions to do just that, it will save much time and effort.
I did not use the thin/light-weight 1/16" rod for the sensor link/connection. I used RC model parts, two swivel ball joint ends, one jam nut, installed on a steel welding rod with 4/40 die cut threads held to the sensor on the crank with small RC hardware machine screws and nuts. I drilled a #44 hole.