kylightening

i just pulled my sons gas tank. he has a 86 stepside that was sitting for a while, it came out as a 6 cylinder but has been changed to a 302 carb engine. the tank is rusty and the sening uint bad. looking for the right one. here is the problem i think it is a 16 gal tank but the sending unit does not look like any for that year. it is more like a 84, could they have just changed the sending unit to a carbed system. mine only has one fuel outlet and 2 prongs to the elect. or was the tank changed also! will the 84 sending unit fit in the 86 tank? any help will be soo good right now as he is driving my truck! till i get this fixed!