I really need some help figuring out why my truck isnt running. its a 1979 with a 20r. i let the truck sit for a while because i was doing some tranny work, i get back in to start it and it wont crank. so i jumped it. and it worked, until i took the jumper cables off, than the truck died. so i replaced the alternator. truck is still having the same issues. please help! any ideas would help! i already checked the fuses, and the engine fuse was blown, so i replaced it and nothing changed.