First I would have to state that we have found things (as we have in the assembly manuals) in the MPC that are different from what was done at the factories
The MPS (as you wrote) shows the C5ZZ-3352-A idler arm as being marked with a brown mark and the C5ZZ-3352 -B with a blue. Earlier versions of the MPC (ones I have) do not list any color codes
Guess this is what you found - the picture was listed as C5ZZ-3352 -B the PS unit
But also have C5ZZ-3352 -B boxes as these marked with a yellow (also have a PS 6 cyl idler arm marked with yellow like later cars)
Will look through more of the files and documentation while others comment and share