Does a '98 Dakota have a donut gasket between the manifold and the catiletic converter

The gasket between the exhaust manifold and the pipe is called a donut, because of it's shape. Try tightening the bolts, else replace the gasket

This is going to be a pain, due to the age and rust. I assume when you say upper exhaust gasket. You are referring to the manifold to head gasket. If so you need to soak the stud/nuts with PB Blaster lube then back out the nuts, to remove the manifold. For the lower gaskets I assume you are referring to the donut gaskets where the pipes meet, I am pretty sure this model does not use donut gaskets.

stop into a parts store and ask them they will know as they sell exhaust systems.

You have a leak in the exhaust system. Have it looked at soon. You don't want to be breathing carbon monoxide while driving. If you hear a "ticking" sound while the engine is running (more predominant with a cold engine) it's most likely an exhaust manifold leak, either a bad gasket, broken stud or cracked manifold. Other possible causes could be the "donut" gaskets that seal the Y pipe to the exhaust manifolds, the Y pipe to catalytic converter gasket (if equipped).

All vehicles have some sort of break in the exhaust pipes, thus creating the need for either a flange, or donut type of gasket to join the connections together. The most common place of use for the gasket, is below the exhaust manifold/header, and the Y pipe that connects the manifolds together.

You state that car makes a loud noise when driving. Do you notice the sound more when you accelerate? If yes, then it could be either the exhaust manifold gasket or the donut gasket. The donut gasket is where the exhaust pipe connects to the exhaust manifold.

the donut is cast into the exhaust manifold.

Yoou shouldn't have to remove the radiator for this fix. I would recommend using new gaskets and donuts due to the replacement manifold being used, it may be slightly warped from heat, would definately replace the gaskets and such. Hope this helps.

HI, check the exhaust manifold gaskets. they may need to be replaced. these gaskets will leak overtime, causing this issue you are experiencing.

There is also a gasket(donut) that is located in between the exhaust manifold and catalytic converter as well. this amy be leaking as well. check all the above and, replace any failed gasket

Are you asking a question or just making a declarative statement?
Unlikely you have holes eroding in the manifold, check your gaskets & donuts first. If you replace the manifold gasket use new bolts when you put it back together with anti-seize compound and use a flat edge to check flatness of both faces.
I once had a corroded oxygen sensor that sounded like a bad donut gasket. It got really noisy all of a sudden and I noticed one part of the oxygen sensor hanging by its wire and the other stuck in the manifold with a hole blowing exhaust where the sensor used to be. Pretty obvious what needed fixin' after that.