Do you mean you want to distinguish the in-hose from the out-hose or you don't know which hoses the heater hoses are compared to other types of hoses?
As far one versus the other, I'm not sure (I have a 1992). But I do recommend you get a Haynes manual or some other manual before proceeding. This will help you with your do-it-yourself work.
For the 1992 models at least, Ford recommends first back-flushing the system and then flushing the heater core by itself in the OPPOSITE direction. If this is the same for your model, it is easier if you get two Prestone kits - one Tee for each hose - and two additional lengths of heater hose - 4 feet each maybe.
1) After draining the antifreeze, put in both Tees. Attach one of the extra heater hoses to the pipe thing Prestone gives you to stick into the top of the radiator. (This makes it easier to capture the water as it comes out of the top of the radiator and run it into a trash bin or something.) Flush through the inlet hose - if the inlet is what the manual says (I don't recall - maybe someone else here know which of the two hoses that is.)
2) Then disconnect both heater hoses from the engine side - to isolate the engine during the reverse-direction heater core flush. Attach the garden hose to the Tee and block off the open end. Attach the spare heater hose to the open side of the outlet hose and run it into your trash bin.
3) Turn on the hose to flush the core.
A couple of points.
I think I DID use a Prestone system flush. I see there are differing views about whether one should use a chemical flush as opposed to just water.
The only tough part here is figuring out how to capture all that antifreeze and disposing of it. I used a big plastic trash bin. I caught everything until the water ran clean for a while. But even then, it took me lots of trips (over weeks) to my town's recycling center to dispose of the stuff I collected. It wasn't very green, and I got criticized by the recycling center attendant who said I was watering down his antifreeze reservoir too much. But so be it. (By the way, while flushing the system, after the water ran totally clean, I let it run onto the ground. No way I could have captured everything. I did put the trash bin back when I flushed the heater core, and caught a lot of what came out of that.)
Also, I too was changing the thermostat. I decided to remove the old one, reinstall the cap and flush BEFORE installing the new one. That way I was sure everything was wide open. If you don't want to bother, I would flush with the old thermostat so that you don't get junk into the new one.
Ford says to refill with tap water, so I did not use distilled.
In the second flush ... at about 50,000 miles, I also replaced the radiator hoses. It was hell getting the old ones off - no room to work, and the old ones were fused onto the pipes. They also were like new.
Enjoy the job. Good luck.