98 12V maint questions.
 

So, my 12V has 56k on the clock, when I tear it apart to tab the KDP, I also will be changing the coolant, all hoses and belt. At this mileage is it worth it to change the water pump and idler pulley for the belt?

no more miles than your truck has they should be fine. but its a cheap and easy job that could keep you off the side of the road later. if you have the time go for it