I also have a d2 (Extreme, not Quadra) which is on the fritz. Thought it was power-related, and got replacement power brick on advice of LaCie tech rep. Got it in, still kept getting intermittent power with some whine from the brick.. which leads me to believe that it's the brick.. but when I move the 4-pin connector on the drive, it will fritz... even thought it's not loose from the board inside (I looked). So anyway, it's a Samsung drive inside.. what kind of enclosure can I use? Sorry, I'm tech-savvy (lifelong musician, and visual performance artist), but just haven't dealt with drives too much.. (Hence owning the d2).
Goodness, a thread from 2006
Basically any 3.5" enclosure will do, they normally all come with a new power supply / ac adapter.
However... That drive comes with a 3 year limited warranty. So if the content on the drive is not important, contact LaCie and return it for repair / replacement.
If the content is important - as I say any HDD 3.5" external enclosure should do. How expensive it will be will vary on the amount of ports the enclosure has on the back.