I'm looking, havent found anything either.
Parts are found in Treasure Spots around the galaxy (not the Dreadseeded ones), you find them with your Macrobinoculars, and then go search them. From what I've researched, each area has ONE specific part to a specific speeder, and once you've found that part, then the area is useless.
Treasure areas I've found :
Black Box heroic area on Tatooine.
Near the imperial base near Northwest from the Highmount Ridge imperial base on Hoth.
"Nerf vs. Manka Cat" : Area on Alderaan near the Oval shaped palace on east part of map.
Wampa Vs. Tauntaun : Directly east of the Republic Base at Highmount Ridge on Hoth.
Toborro's Courtyard : Makeb (Confirmed drop of Music Transiever for PMP Pleasure Speeder
Volcanic area behind Snowblind's lair (Level 55 area) Hoth