There is a fitting on the firewall to which it connects. This fitting is small, it is behind and under one of the AC hoses, and unless you know EXACTLY where to look it is nigh impossible to find.
One of the guys on the Escort forum posted this image:
The blue circle is where the hose goes. There's a lot going on there but having seen this image, I was able to concentrate my search on that area...and found it.
The hose is installed; reassembly of the Escort is now 100% complete. All that remains is diagnosing and fixing the stumbling problem.