These seem to stop dropping entirely past level 45, thus making it impossible to finish collecting and assembling them for the quest.

[edit]
Ok I'm still getting a drop now and then but the drop rate does seem to have tanked noticeably after 45.

I only have first parts... (You get them with a low level character because you have to hit the mobs at least 2 or 3 times. You not must oneshots the mobs.)
BUT REALLY go your way it's a waste of time