Hi.
have an 03 1500 with 4.7. it's a 2wd quad cab model. Upon inspection of brake lines I noticed my diff breather had snapped off at the axle . Soi decided to check the fluid to make sure it was full and still clean. Fluid was a light coffee with cream color. So I need to change it. My question is will this cause it to whine. My father said I should rebuild the diff. On a bit of a budget due to Covid crap. Any ideas of the whine. Also how do I find axle ratio and diff size. Or should I just buy a whole used rear axle and swap it in.
Thanks

 

Why rebuild..it's not whining right now, right? New fluid can only help. Leaving that old fluid in it may make it whine even quicker. You may have gotten in a bit of water, so change it quickly as possible. Not sure how you'll fix the breather. Maybe gently weld it on? Maybe others can chime in on that.

 

I *think* the nipple for the axle vent just screws into the axle tube, and holds the junction block for the brake lines in place???? That part should still be available.

 

Correct

 

It does whine a bit. Mostly at acceleration. When it heats up it will whine while cruising. On the highway after driving 30kms at 115kph it starts to getting louder. As for the breather, it's rotted right off at the axle.

 

Unless it is so hot you can't touch it, I would use it until it is really bad. From what I have seen, it is something of a process to set up a rear end in these trucks. Just make sure you are using the correct oil in it.