My YJ had set for a long time before I bought it and it leaked in the same area. I tried a couple stop leak additives with no luck until I bought some Lucas power steering stop leak. It works pretty good. You may want to try this first.
Nothing is foolproof to a sufficiently talented fool.
Loic, yes, that's the pitman puller. Just rent it from a local shop and take it back when done. (it ends up free). Just make sure you get a heavy duty one as it's a bit of a bear and hit the area with PB Blaster a few times. Makes life a lot easier.
I installed a PSC Power steering pump last month and that ended up having a little more oomph than the Durango steering box could handle and ended up leaking in the same place yours is. I have learned years ago working on my Dodge Rams that the steering boxes you get from " any " of the local parts places are hit or miss as to if you get one that works right and lasts . I cured tha Dodge steering box issues with a PSC steeing box ( price dropped lately from 349 to $279.) so I just installed the PSC in my TJ . You will find when it comes to steering gear you usually get what you pay for in relation a new OEM box or a PSC .