Welcome to your first post.

There is nothing wrong with the Gen I rear axle, you already own it. The seal is not too difficult to replace and is much less work than swapping in a Gen II axle. I won't go into the Gen II axle topic too much, because there are numerous threads documenting them. The benefits are a wider track, disc brakes and an air-locker (not like ARB).

I'd just replace the seal and wheel bearing, turn the drums, adjust your brakes and be done the same day.

Russell

1987 Raider - Roxy
1988 Mighty Max 2.6L Turbo - Pearl
1997 Mountaineer V8 - Freddy
2000 Excursion V10 - Freya