I have a friends truck (99 3500) that has a serpentine belt problem. he bought it not that long ago and since he got it the serp belt was a groove off towards the engine but it never shredded. over time it did shred a rib off and he wanted it replaced before his camping trips. so I replaced the belt and tensioner which did have some play in it. well he had driven the truck for a week or two and left to go to a local campground and on the way the belt shredded and flew off. we were able to loan him another friends truck so he could finish his camping trip and I took the truck back with me. my question is, is this a common problem? not much has been done to the truck in terms if belt driven parts replace. he has several long drives planned so I need to get it 100% ready. from what I can tell none of the pulleys have any play in them at all. the last thing, I noticed the coolant is pretty nasty so I was going to do a flush. is there any brand of coolant I should use that is better?