The Rectifier family of modules used their own PCB. There is a common misconception that a given part number will always play the same role from module to module. This is not the case at all. Any given part number can play a completely different role from module to module. This includes both the four different PCB's used in the system and various revisions (the Brit PCB alone had 5 I can think of off the top of my head) of the boards that were used throughout the 10 years the line was in production. This is the exact reason I was hesitant to support the spreadsheets that the community worked on a few years back.
When designing a PCB, most software programs will auto assign a number as a component is added to the layout. That is how you get R1, R2, etc. It has nothing to do with "R13 will do the same thing on every module, all the time". If in doubt, trace it out to determine a parts purpose.