Not wanting to step on Ric's toes here, but I don't trust the nut on the axle to keep that drum from flying. I've done this several times. Each time I use a chain. Put at least one link on a stud then put a lug nut on it. Wrap the rest of the chain around the leaf spring, with enough slack to let the drum pop loose but stay at the end of the axle. After you put the puller on and whack it a couple of times take yourself out of the line of fire. Get to the rear or the front of the drum to save yourself. The last time I did this I swear that drum would have gone through the side of the house if not chain restrained. Be careful!
After the initial removal they come off easier, but I still ALWAYS use a chain.
I read the links below and am using a similar puller to the Kaiser Willys product without any luck. I started to bend the puller. I have used lots of penetrating oil. Any other suggestions? I thought about heat, but where exactly do you apply it? Thanks for any suggestions