I have a 94 Silverado. I'm going to change the thermostat. In the past I have used the paper gaskets that fit around the water outlet housing. There is also a rubber seal that pops up when doing a search for thermostat gaskets. Should I use the rubber seal and place it in the thermostat housing and use the paper gasket for the water outlet housing?

If it uses the rubber seal, you usually don't need the paper gasket. The seal compresses and seals the manifold, T-stat, and T-stat housing