After further screwing around, there is no hose, there is only a foam gasket sandwiched between the plastic part of the heat/ac unit and the floor board, the gasket has degraded and now it's leaking, not a great design Chrysler, it did last for 25 years however...
Thanks for the Eyes On video. I just bought one of those with 170K on it. No sign of past water, but I'm girding my loins for future issues. They're great rigs, but do have idiosyncrasies.