the dracon beams are fairly well described, and in one of the books (andalite or hork bajir chronicles) it is stated that they are adapted from shredders, in fact, the andalite picking them up didn't know they had been changed until the examined them more closely. given the rate of change of yeerk technology and the fairly short timescale of the series, it leads me to believe that shredders looks a lot like dracon beams.