Have a NOS Suntour ultra 7 freewheel, two prong. Beautiful condition, but towards the end of the first ride on it, about 50 miles, I started hearing a loud squeaking, almost like brake squeal, coming from the freewheel when I coast. Any ideas on the cause and how I can fix it? I'm thinking the grease inside the body has dried out. I know these can be disassembled, but that's beyond my capabilities.

You don't normally need to disassemble a freewheel, ever, unless the pawls are so worn they won't engage the ratchet. But even then the problem is often that the pawls hang up due to no lube, or grease that's too stiff. So....
Hold the freewheel horizontal. Find the interface between the moving and stationary parts on the top (small-cog side) of the freewheel. Dribble your favourite solvent or degreaser into that gap while you let the two parts click past each other. It's often easier to leave the freewheel on the wheel while you do this, except then dirty solvent will drain out the back of the freewheel and get all over the hub. Then dribble in lots of light motor oil -- use a teaspoon or so to make sure there's enough to find its way to the lower race of bearings. Keep spinning the freewheel while you do this to encourage the oil to penetrate.

Now is the time to remove the freewheel from the hub. Leave it sitting in a tray for a day or two to catch the excess dirty oil that will eventually leak out of it. It should spin quieter now. The clicking might be louder, but it shouldn't squeal. If this doesn't help, well, you're not supposed to be coasting much anyway....

Some Suntour freewheels have a rubber? seal at the interface that you may not be able to get solvent or oil past. I don't know what to do with these, since mine ran trouble-free forever.

good advice.

PM sent.....

. new winner pro had labyrinth seals , oil hole is inside the part that threads onto the hub.

^ Dang, you're right, Fietsbob! I had forgotten all about that oil hole. Thanks!!