What could be leaking into passenger floorboard in 79 corvette?

I am not sure, but it sounds like your heater core may be leaking. You may be lucky, and only have a hose leak. But most of the time its the core that goes bad and needs fixed or replaced. You may check under your hood and look at the two hoses that go into the fire wall on the right side of the car. If your lucky one may be leaking at the clamp and only need to replace that clamp. But most of the time it will be the heater core in the fire wall that's the problem and need's replaced or fixed. If you need to drive the car before getting it fixed. You can take both the hose's off the core at the fire wall. And connect them both together with a two or three inch pipe and two clamps. This way you can still drive your car until you get time to have it fixed. Be ware though that by placing both hoses together you will not have a heater. Good Luck M.C.S. The Missouri Crack Shot.......