I can't claim any first hand experience working on a 2wd 3500 but what I'll recommend are universal tips.
I assume that you are certain that your cups fit around the old joint and have plenty of depth to receive it without bottoming out the press? Also tension the forcing screw and then bang the hex head of the screw with a hammer, give it a couple of pretty sharp raps, you may need to do this a couple of times as the joint comes out and use at least a 24 oz hammer as a lighter hammer doesn't generate enough force in the room that you have to swing it. Some penetrating lube like Kroil helps too.
Two more things about your rented press, lube the screw with something that will not be readily displaced by the force you put on it and check to be sure that the press is truly square, not sprung. If the press is sprung and thus not pushing straight through the bore, you will never break that joint free.
If all this fails I have cut them out using an oxy acetylene torch using an asterisk pattern across the top of the joint and then bang them out with a good size hammer, I think my favorite is 32 ozs. Don't worry about cutting the knuckle or control arm if they are cast, not gonna happen. If pressed steel, you have to be more careful. Don't be alarmed by the resultant flames, but you may want some form of extinguishment available if they get out of hand.
Sometimes working on equipment is a lot like making sausage, if you know what I mean, the process isn't very appealing but the end result is desirable.