I have a 250gb Passport from the original design that has a removable SATA to USB adapter that easily pops off. I swapped it with my other Passport and it works perfectly. I see many ppl just add it to a new external enclosure, but I would prefer to replace the adapter & put it back in the WD case. I have a bunch of externals already and need the small size of this when working. Is this part sold by WD? Is it available anywhere online? I hope someone has the answer 
I searched but could not find any info on replacement adapters. The drive & adapter is identical to the one in this link: http://www.devincollier.com/2010/01/04/how-to-open-a-western-digital-elements-500gb-2-0-portable-hard-drive-case/comment-page-1/#comment-360 THANKS
WD does not sell replacement parts, any external USB SATA enclosure for 2.5" drives will do the job.
I was not able to find anything like that either. It has been discontinued probably.
