David Bean asks "...On 5 speed Suntour freewheels, are the two smallest cogs the only ones that are threaded? And the other [splined] ones can be flipped over in order to wear out the other side of the teeth?..."
Yes. No. If I have it right, the freewheel cog teeth have a profile and are not symmetrical. The straight side of the cog teeth faces outward towards the rear derailleur, to facilitate chain pickup when shifting onto larger cogs. If you turn them around, they will work but your upward shifting may/will suffer.
Peter Brueggeman
La Jolla California USA
pbrueggeman(AT)ucsd.edu