GM-GMC: 87 Gmc truck charging issues, gmc suburban, gmc truck

Question
Hello i have an 87 Gmc Suburban that is having electrical problems. the battery gets drained after sitting a day or two and when i drive it the guage only reads about 13 volts, and still the battery drains while running and eventually dies. i have looked at every wire i can find and cant see any burnt or cut wires that would cause a short. ive checked the wires at the starter and alls good there, ive installed new battery wires. ive replaced all fuses, the battery checks good every time i go to autozone to check it, t just replaced the alternator twice in same week and neither alternarors do different or better the truck still wont charge, even when running if i unhook the battery the truck will die but every time ive had the alternator checked both in the truck and out it checks good, i cant think of anything i havent done and it still isnt fixed can you halp me please.

Answer
From what you are describing it sounds like the alternator is not charging the battery.  Check your battery ground wire, double check the charge wire from the battery to the alternator and triple check that with the engine running you have 12 volts at the terminal on your alternator.  That terminal is what tells your alternator to start charging, you need to have power on that wire with the engine running.  I have no great insight other than that.  If you have had your alternator tested on the truck and it checks out ok.  (around 14 volts and atleast 65-85 amps) there is no reason it shouldn't charge your battery.
Hope this helps