The past few days I've been working on getting all the parts. I've gotten most of the non-pickup parts so far. Working on S-ranking then going back and getting the pickups.
The part lists available are somewhat unreliable on gamefaqs. Fortunately the game comes with one via the connect's regulation feature. However, I noticed 2 parts that are not on the list, and googling did no justice, especially for the 2nd part.
[Arm Unit R] -> [EN rifle] -> [YWR27HL-KRSW2] "KRSW laser rifle modified for higher energy output."