My Ford 4000 power steering ram is leaking badly from the ball joint shown in the attached photo. It will bleed out the entire contents of the resevoir/pump in about 4hrs of working.

Where can I find a parts diagram or listing of what parts I need to repair?

View attachment 52437

I assume you have the I&T FO-31 manual. If not get it.
Overhaul and reseal on that cylinder is covered pretty well. Parts are still available from CNH. They are not difficult to go through.

 

Here are two threads regarding similar problem:
https://www.tractorforum.com/threads/confused-on-my-power-steering.35709/
https://www.tractorforum.com/threads/power-steering-cylinder-4000-ford.35970/

Online parts lists:

https://www.messicks.com/nh/138355
Choose
06 - FRONT AXLE & STEERING
then
03D02 - POWER STEERING CYLINDER, 3500 (65/72), 3550 (72/) & 4100 (65/3-70)

This covers the non available parts as well:
https://avspare.com/catalog/newholland/64887/20597/259191/

*** Edit
Updated parts list
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