[dsraven]

question, is it an old battery that you thought was gonna die one of these days anyway or was it a relatively recent battery and you were surprised to find it dead?
if yes to second answer, ask yourself what parasitic loads you have in your truck that could slowly drain a battery. clock, radio, security system etc. if you have those type of small loads then maybe you want to install a battery tender that will keep up to those loads. if no parasitic loads and your previously decent battery is stone dead you may wanna look at other reasons why. sometimes it's because it sat too long without charging and then cold weather caused it to diminish and it finally froze. when they freeze the plates can get seperated and distorted or the case can crack and leak the acid out so when it thaws it just isn't the same anymore. it could low on acid and the area above the acid sulphates and no longer reacts. anyway, it kinda makes sense to answer these questions before you simply place a new battery in and assume it will be all good.
another thing to mention is that when a battery is low and the vehicle is started without charging the battery for a bit first, like mr48 did with using his mower to charge, then the alternator works very hard to charge the low battery so it takes a bit of lifetime off the alternator and the battery or, worst case scenario, the alternator overheats and burns out.
a quick way to check for a parasitic load is to use a volt meter between the battery post and the cable when you are connecting the new battery. one side connected and the volt meter on the other side. if there is no load the volt meter will say zero. if there is a load, like an interior light is on or something ele, then the volt meter will register a voltage. finding that becomes the next thread.