Heat/No Heat - Thermostat?

Currently, the temperature guage warms up to just under 200 C, the ramps quickly to 260+. I turn the van off for a short period of time. It cools back to under 200. I suspect that the thermostat is or has gone bad, but where is it. I have pull the upper hose off, but do not see the on either end. Thoughts or suggestions anyone?

This doesn't necessarily mean bad thermostat. It could also mean low coolant, air bubbles in coolant, head gasket leak, or temperature sending unit failure (all of these are common problems with these vans). Pop your radiator cap and look for peanut buttery substance on the bottom or in the radiator. If you see this, RUN, don't walk to your nearest repair shop for intake manifold gasket replacement. This will also involve a fluid flush and bleed, which would clear up any air in the system.
The thermostat is located on the upper intake manifold, its really a pain to get to. Just follow the other end of the hose to the intake and you should see it burried back under there. Pick up a haynes manual for specifics.

I should look for this substance into the radiator, mixed with the antifreeze.