So for the past few weeks I've been getting a really weird grinding noise coming from the underside of my truck. It only seems to happen when I'm about to shift or when my truck is trying to go up a hill. But it also seems to be not nearly as bad when driving on smoother roads.

I tried putting some extra gear oil in my rear differential, hoping it was just some low oil. But I was only able to put a little in before it started pouring out.

I just recently straight piped my exhaust due to clogged catalytic converter that was causing leaks and I didn't start hearing it until after it was fixed. Honestly though I'm not sure if I wasn't able to hear it because of the exhaust or if I somehow caused it.

I think it might be the exhaust not being mounted correctly because of the inconsistency. But I'm not sure.