I have had a lot of trouble keeping the belt on my 4.1 POS since I owned it. I bought a new tensioner when the pulley went bad, but doesn't line up very good with the rest of the pulleys. I had to make some tapered shims to tip the tensioner a bit, to keep the belt on. This this thing has went through more that six belts since I owned it. I'm beginning to wonder if the mount casting that holds the alternator ( that's new too ), is possibly bent (?) Not usual for a casting to bend, but it sure doesn't hold things in line very good. I'm also wondering where I can find another mount casting, which may be better than this one (?)