Camshaft

First, "went out" is hard to define. If the lobes of the cam have worn down for some reason, the metal that wore away is now circulated through the engine. The rest of the engines parts have seen significant wear from this and won't last long. You could throw another cam in, but don't expect the engine to last long. You need to find the reason for the cam "going out"

A brand new GM long block with a warranty is available for your truck fo less than two grand. This is the route I would go. if you do install a cam in your present engine, at least pull the oil pan and inspect and clear out any metal from that worn cam. I assume that this engine does not have roller lifters, so you should be using an oil with the ZDDP additives such as Royal Purple HPS or Amsoil Z- Rod. Also use proper break in oil with the new cam or engine or you have the same problems occurring in the near future.