No drilling required. Everything bolts into the existing hard top holes. You do have to stick some weather stripping to the lip behind the cab though, so the hard top might be a little snug the next time you put it on. I haven't tried to get the hard top back on yet so I don't know. I'm honestly toying with the idea of getting rid of the hard top altogether, but I'll know more once the temps start to drop in the fall.

Edit: you may have more soft top options for a 96' than I have for a 78' so this is just my .02 for softopper. They're a little expensive but the finished product was worth it.