I have a 1991 explorer with automatic locking hubs. When I switch from 4H
to 2H, there is a very loud grinding noise when driving forward. If I
disengage the hubs by backing up, then the sounds goes away. It also
sometimes does it when I drive forward in 4H. I noticed it started after
I was trying to gain traction on ice and I put the truck in 4H right
before backing up. I am pretty sure its one of the hubs, but is there
something else I should look for? I just had the 4wd motor replaced a
couple months ago so it shouldn't be that. How could I check to make sure
what it may be. I have also seen some postings about changing from auto to
manual hubs. Is this advised?

Thank you,

Josh