The shoulder armor is called a spaulder. It's a predecessor to the pauldron, which covered more and was usually made of overlapping plates, like an armadillo.
Right shoulder armor is more brown than PP2
Left shoulder armor is similar to PP2
Left shoulder armor is "golden yellow and weathered where indicated in visual references to give the illusion of battle wear and damage," which has the Mandalorian skull symbolSource: 501st CRL
Left shoulder armor has the Mandalorian skull symbol
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Compare side-by-side costume differences across different colorways