What's next?

Well got my truck back after new radiator tranny and fuel thingy. Andy they tell me my belt needs replaced too. Before I had the other stuff fixed it would whine a little when first started but oh my now it sounds like a locomotive trying to stop. I had it replaced at 21,000 miles under warranty for doing the same thing. 40,000 miles later here we go again except this time I will be paying. How much this usually run or can my dad and I do this? Thanks guys.