Short version:
If your rear pinion seal is leaking, change the diff fluid when you replace the seal
Looking for opinions on if I actually need to change the rear end and if so, what do people suggest?
Long version:
The ring and pinion has always been loud since I got the Jeep with around 87k miles in 2012. Recently (since April 2019 when I started driving it again after it sitting for nearly 20 months) the rear end was also making a bit more noise than before....almost like a bearing might be going....on top of the rear end whine. Lifted the rear and wheels seemed okay for play to indicate it isn't a bearing issue. Opened the diff and oh boy, very milky. Wasn't over the drain plug level though. This was quite surprising considering I changed the diff fluid about 40k miles ago. Not sure if water got in due to a leaky pinion seal I had earlier (but still post diff fluid change) or if it sitting for so long some how got a lot of moisture in the diff housing.
Changed the fluid and added the friction modifier. Definitely helped with the noise, but still a bit louder than it used to be.
With the noise and the issue with it running with water for some period of time I was doing some research and it appears I have 4 options:
1. Ignore it? - The rear end has been making noise since I got it and hasn't had a noticeable step in noise increase besides this recent issue. The gears look pretty good, but some slight play. Is there really an problem with just to keep driving it as is with the noise? I could understand if there was considerable slop or vibration, but it doesn't seem excessive.
2. Rebuild the rear end - New ring and pinion, axle bearings, and possibly diff and you are looking at $500-900 in parts and $600-$1000 to have some one rebuild it (not sure if this is something I'd be willing to tackle....I mean for $1000 I'd give it a shot)
3. Swap in a Junk Yard Axle - seems you can get junk yard replacements for ~$350 to $600. However most of them have >100k miles on them and I don't want to spend the time to swap an axle just for the same problems to occur again. On the flip side, if I can swap the front and rear to get the 3.07 ratio, then I'd be interested.
4. Buy New Axle - For money, what am I missing about buying a new axle assembly such as this for ~$1300 shipped?:
https://www.moparpartscorp.com/oem-parts/mopar-axle-assembly-5191214aa It may not have the electronic limited slip, but not sure I'd miss it if it is new and saves me $1000?
