need help

on my 82 720 my battery was going dead and i could take the neg battery cable off and it would die so that told me it was the alternator so i got a rebuilt on it but it still dies when i take the neg cable off. anyone know what else this could be? also noticed i aint got no tail lights now but i do have turn signals dont know if the two problems are related or not. is there anyway i can straight wire it to see if that will bypass the problem?
i am about ready to take the truck to the crusher it is starting to piss me offhttp://www.nwde.org/extras/forum/smileys/smiley7.gif