If you have a working one in any of the boxes, remove it and determine the characteristics of it on the bench before shopping for the replacements. 
OK.. Since my last post.. The 2nd led went dim on my 2nd box.. Let me just say though, that my 323's run 24/7/365. That makes all hard drive led's on my two boxes have failed.
Soooooo.. I did what you said and figured out the led on the bench.
Center pin is a common anode. The pin on each side are the cathodes for each color, one blue, one amber.
That makes the led for the hard drives: 5mm, semi diffused, common anode, blue & amber led.
I have spend hours seraching.. The common anode is the problem. If it were a common cathode, no problem. If you don't mind clear instead of semi-diffused, you can get blue & red but still common cathode.
If anyone can find a led that would fit.. Blue is a must, but the fault color can be red instead of amber, post a link. I can find nothing.