i have got a 2005 f150 that i recently swapped front diffs out of a 2004. went up to a 3.73 ratio with both diffs and now got the limited slip. but now when i use 4x4 i get one hell of a grinding noise most prominent when im going from a dead stop and hammer down on it. seems like any bit of wheel slip results in a big bang or a grinding noise as soon as that wheel grabs traction. also notice it when im stuck and have to rock the truck back and forth by going from reverse to drive. (not abusing the truck just lightly rocking) almost seems like a loose pinion but checked everything that is visable to touch and nothing is loose or anything that i can see.

 

https://www.f150forum.com/f72/how-di...m-esof-186872/