All the hoses on my 88 GT were original but I wanted maximum reliability so I replaced all of them. I didn't make a list of all the part numbers, but I can tell you they are hard to find. Autozone only has three of the five primary cooling hoses.
EDIT: Deleted misinformation about lower coolant hose on passanger side. I didn't know Rodney has them too.
[This message has been edited by 88cryan (edited 06-06-2015).]