Yea but odarkstorm gets extra range, i used normal darkstorm for last event ultra bases needs added range. Also gets added speed. I search entire map haven't seen an edarkstorm all year. I managed to get 3 parts i am a returned player been back around a year, the bases disappeared around when i came back. I have all ods parts but useless if i can't get eds.
There are daily drops for old Unique Units, however there is only one of each (i.e. standard, Elite & omega.) You will have to search the whole world map to find them. Once you defeat a base it will respawn else where on the map in a few hours. Note that these drops do not occur during the monthly event.
I was in the same boat not so long ago, it was a pain! But kept looking out for the Elite DS bases and grabbed them whenever they were available, eventually got all Elite parts while already having all Omega parts.
Since it's a legacy unique it doesn't follow the unique's spawn schedule and just drop randomly (at a very low percentage)
The good thing however is that a lvl1 ds got almost no difference to a lvl40 ods (cause both gets 1 shot anyway, and the aura doesn't get any bigger)
Darkstorm used for aura only