I had my brakes replaced and once I picked it up from the shop, immediately had a grinding noise that sounds like your running over a never ending rumble strip.

I returned it to the shop, they said that they had unhooked the vac lines for the four wheel drive and forgot to hook them back up? so they did. noise continued. I was able to get the noise to subside by switching to four wheel drive....????

Ultimately took it to the Ford dealer and they diaged it as the splines were shot on the front differential. ended up getting the repairs covered by the original shop, but they could only replace the front diff with a used diff due to zero availability on new.

the problem was resolved for about 4 months. Now, the noise is back (intermittently) and I am able to get rid of the noise by pulling over, putting it in park and then drive again. I sometimes have to do that 2-3 times until the noise goes away again. I have also noticed that the noise seems to be more active when it rains/wet road conditions. But not always.

Anyone have something like this happen and get an actual resolution? I'm worried that I'm making it worse the more I keep driving it. I recently took a 500ish mile trip and didn't have one single issue to tell you how intermittent it is...

 

That sounds like an IWE problem, not the differential. So, they did a lot of work and didn't fix the issue. You most likely need new IWEs, but it could be another part of the vacuum system, as well.