Hi- your second photo shows a pinion… and it doesn’t look too bad. Might not leak. First photo shows an output shaft and it is leaking. The “trick” doesn’t work with output shafts seals. Plus the bearings are ALWAYS toast due to the way the output shafts serve as upper control arms of the IRS. Anyway, it’s a doodle for facelift cars with outboard brakes. Get new bearings and seals I. A single kit from SNG Barratt or whoever. That’s FOUR bearings. You unbolt the out shaft, unbolt retainer, and remove two bearings at once pulled out from each side. Then you rebuild assembly on the bench and install again. There is a crush sleeve in the kit… I’ve done the preload method with a new crush sleeve and I’ve reused old crush sleeve with new bearings and seats and neither has been a problem. If old bearings and race are same thickness as old when measured with a micrometer there’s no reason the put in a new sleeve and crush to spec… the old sleeve will be close enough. Anyway have fun, you seem like the brave type from past posts here.
Regarding the output shaft seals, the complete output assembly with new seals and bearings is available from the usual’s. That might be a better answer than removing and stripping down yours. I have rebuilt my output shaft assemblies on my inboard brake 89, it was not difficult, but required a pretty giant socket and a little bit of fiddling. I don’t know the differences for outdoor brakes. Forum search will reveal a lot of posts about rebuilding output shaft assemblies.
I recently had an output shaft assembly with bad bearings rebuilt on my Salisbury diff by Coventry West. About $200. Took just a few days, including shipping. My car has outboard brakes making R&R of the assembly easier.