You'll need a couple of special tools.

First are spring compressors. The stock springs extend realyl far when unloaded, and they are restrained by the strut plate on top. So the spring needs to be compressed before you can move on to the next step of taking the top nut off, which holds the strut plate on.

Which leads to the second special tool - the nut is recessed somewhat, and you can't just use a socket on it because the shaft will turn and there's no real good way to hold it. There's a hex opening in the end to counterhold it, but it's recessed so you can't get a normal box end on it while you use an Allen wrench to counter hold. So you either need a special tool that's basically a socket with a cut out side, or you need to use an impact wrench. Hint: One of these tools is more useful the other 99.9% of the time you aren't putting struts on the car.

Then there's the large gland nut that holds the strut in the tube - in theory you need a special tool for that but I just used some very large channel locks.

Earlier cars had slightly larger diameter strut tubes (the long tube the strut fits in side, with the spindle at the bottom that holds the wheel hub). And they had spacers in the bottom to make the stock struts fit properly. Bilstein HD's fit fine in them, but on later cars the tube diameter shrank slightly, and the spacers were either eliminated or welded in (i.e. there's nothing you can remove), so Bil HD's are practically a no-go on them. On mine I had to peel off the very thin stickers on the struts so they'd fit, and then had to leave the gland nut only partly screwed in as the strut is a little too long for the tube. I used loctite and (IMO) had enough threads engaged to hold, but it's not a great feeling. But it's been like that for a couple of years now, every once in a while I peek at them and nothing's moved.
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'63 PV544 rat rod, '93 Classic #1141 245 (now w/16V turbo)