[morzh]

I never use either the rod or the can as electrodes when I rebuild: you cannot (normally) solder to aluminum, and the rod could also be aluminum.

I simply let the wires out of the bottom. Often times if the wire is thick and stubby enough it still can be used as a soldering post (as the rod is often used that way) and the negative could be soldered to a ground post or to an insulated negative post usually provided originally when the can is not grounded (like in 70 or 90).


In this particular (shown in the photo) case you have output contacts that are riveted with negative case: when this is the case I drill through each rivet and also drill through the base; then let the positive wires from the caps out through the rivet (marking them so I don't forget which is which when closing in case the capacitances are equal and you cannot tell which is which), and then let the common negative through the hole in the base.
This has another benefit in case the can was grounded - you simply put the negative wire you let out through that third hole under the clamp and voila - you have a grounded can cap.