Diff oil seal leak

[laguardias5]

Hello all,
It sounds like I found the right place to ask this question.
Recently purchased a '91 Camry base model, 4cyl, FWD, 3SFE w/120k miles for my teens first car. It had been sitting for a a bit of time at a little old lady's house and besides the faded paint, it seems it fairly good condition. I am a basic DIY so I replaced the 4 struts (two completely blown), an oil change, torn rack steering boots, and tie rod ends. CV boots look fine on both sides. No idea if timing belt has been replaced, ever.
One thing I checked while I was under the car was the diff oil (ATF) and it was low and took almost a full quart. I know it doesn't hold much more than 1 1/2 qrts. I now have a "moderate" leak coming from the differential on the drivers side, obviously leaks worse when being driven. I can see it clearly at the diff housing. The pressure valve was gunked up so I pulled and cleaned it and it is fine now, but the leak albeit slightly lessend is still there.
I am now wondering how difficult it is to replace the diff oil seal? I know the half axle must be taken off, but does this absolutely require disconecting the ball joints? How can I tell if this axle is a "snap" on variety as I don't see an bolts holding it onto the diff. Does the center drive shaft have to be removed to get to the seal?
Thanks in advance!

[Doctor J]

In order to remove driver side (short) axle you do not need to remove center drive shaft (which is integrated with passenger side axle, unless you want to do both seals at the same time
The driver seal mainly leaks if it was damaged during axle replacement (hopefully it is your case)
or if the axle bushing in the differential is worn out (like on my car with bolt-on axles but my seals are not leaking)
The new seal should probably help anyways.
to remove the axle you will need to unbolt balljoint housing from the steering knuckle (2 bolts 17 mm) it is not necessary to separate ball joint from control arm
Do yourself a favor and fabricate some sort of installer for that seal with pilot shaft which will go into the differential bushing (should be same diameter as this part of the axle.This will let you to install that seal with ease despite limited space.

[laguardias5]

Any easy check of worn out bushing?
Is the only fix to the axle bushing a new or rebuilt tranny?
Should I plan on replacing the ball joints too?

[Doctor J]

Unless bal joint boots are torn or there is an obvious play in it (means the the body of joint offers no absolutely resistance wnen rotated around the stud) the replacement is necessary. However commercially available joint pullers aka tie end rod separators / import pitman arm pullers (from Autozone) are not fitting very well.
I have not found exact specks for bushings, they are usually replaced with differential assembly.
I will say that iin most cases replacement of the seal is sufficient; on my car these wore out due to the running around 5000 mi on VERY low differential fluid about, 3 oz (thanks to previous owner!)

[laguardias5]

Can I replace the ball joints at this time as well or will it require control arm removal?
What's best way to remove/replace?
I've read a couple options with jack and hammer and puller as well as pittman.

[Doctor J]

On my car I removed old OEM joints (to be discarded) by removing the arms, clamping them in the vise and using sledge to knock them out (I was hitting the threaded end , which made it musroom like, but I intended to discard these joints anyway)