The official model name for the HRC's 52" deck is the CD7052. It has a separate parts catalog from the HRC7018 or HRC7020 power unit, which includes the engine, rear frame, handlebars, etc. These were last mfg in the late 1990s, so even clean examples are pushing 13+ years old.
Anyway, scanning the catalog for just the deck reveals many parts have indeed been discontinued for this model, including the front wheel/tire, the side-discharge chute, and the spindle assy.
Caveat: I work for Honda, but the preceding is my opinion alone.