Ball joint grease fittings
 

Getting a lot of creaking from my ball joints and I've tried to grease them, but the fittings are rusted. What type of fittings do these take? Like, size and thread pitch

2000 Bravada

That could well depend on what mfg the balls joints are. Take them out and take them to the store with you. Did you try pushing the ball in with a dental or ice pick?

Yes, I tried pushing the little ball in but it won't go. I'll just do that, take the old ones to the store to match.

I wish I had the time and the space to just replace the ball joints

If they’re rusted that bad, it’s pretty safe to assume you’ve never greased them. If that’s the case, you’d probably be much better off having a shop change out your ball joints before you end up on the frame with a tire up into the wheel well

Theyre toast. They will have metal fragments inside them.

For what it's worth, I've taken closed stems, and left them soaking in a small pool of wd40(or such), for a couple of days(swishing them around from time to time), and freed them to be able to reuse.

not all of them worked , maybe 3-4 out 5 times success rate.

Not a bad idea at all and vinegar is a great rust remover as well. An overnight soak is all it takes but rinse it off or the rust will return.