The guy i bought my 78 from had the conversion done to the ac. The problem is that it leaks all the refrigerant out in a couple of weeks. (You can tell by the puddle.) I cant see where the leak is though. I've looked on the fire wall both inside and out and at all the hoses. Can you guys help?

A puddle of what, refrigerant oil? There is nothing inside the car that could be leaking refrigerant. All components are underhood. Run your hand under the evaporator case on firewall, if you feel oil, it's the core. Otherwise, look above the puddle.