(I would not recommend Speed Racer's method, and here is why.
When you drill and tap that hole, it is possible for some metal "Shavings" or "Cihps" to enter the housing and mess things up good.
Better to follow the instructions.. If that is a Workhorse chassis then there is a thread here in these forums (in the workhorse owner's forum as I recall) that describes it completly.. Hold on and I will see if I can link.
Found it
The Problem
http://oemys-performance.com/library/Brake_Zerk%201.jpg
The Fix
http://oemys-performance.com/library/Brake_Zerk%202.jpg
And Here is where I found it:
brake problem not on recall