Whining somewhere in the rear end

[Jamaka]

Okay, so I'm kinda new here, I've been on this site for around 6 months, prior to buying my x, and have owned my x for about 2 months now. I've searched a lot on here for my problems and fixed everyone one of them so far but two, however one of the two I am still really iffy about(the other I'm thinking is my old PCM).

Before I begin, my truck is a 95 X limited, 4x4, 4.0 6 cyl(of course). When I bought the truck it had a nasty exhaust leak (ended up just needing the flange to connect the muffler lol) and gas tank wiring was corroded as well as a slip from 1st to 2nd gear. Antennae was ripped off, and mirror was broken on passenger side, blah blah blah. Needless to say I've put a few hours into my truck, but I'm concerned now since I fixed the exhaust leak because I've had a whine emerge.

The whine, similar to others only appears after I shift into second(probably because of engine noise in low gear, as well as slower turning drive shaft), and steadily increases while accelerating. It does quit when I let off the gas which makes me immediately think drive train/rear axle. What has me confused is I see a lot about it being the pinion set, or possibly certain bearings, and I only noticed a leak in one spot.

The oil has been pouring out what looks to be my wheel bearing(had a huge amount of grease on my backing plate and edges of the rotor and some on the brake caliper). The reason I'm confused is: I haven't found many postings listing the wheel bearing as a possible reason for the sound, but I know it could be, especially if I'm low on oil, I could be wearing the gears.

The biggest question I have is, should I just go ahead with the wheel bearing replacement, and kind of spot check the other bearings? Or if it's really low on oil when I drain the pumpkin, just take it as low oil and move on?

Sorry for the lengthy post, but money is tight(as with everyone) and I want to make the best investment before I tear it all apart.

Thanks in advanced!

 

[boominXplorer]

Have you check the fluid? The whine would be coming from the ring and pinion in the rear end. I bet the truck has lost alot of fluid and the gears surfaces have started to deform from the heat or bearing fatigue causing a slight change in pattern .

 

[Jamaka]

I haven't yet, I've been waiting to replace the wheel bearing since it needs to be done anyways. Just waiting to get the rear up and pulled open before I did anything else.

 

[boominXplorer]

Once you pull it apart post some pictures if you can. How many miles on the truck?

 

[Jamaka]

Trucks got ~180k, once I pull it apart ill throw some pics on. Just waiting a little bit, need to borrow a jack lol, my buddy at work borrowed mine and broke it.

Also, for the 75w-140 gear oil, is there something else I can use safely? I'm having trouble locating it locally.

Thanks again!