90 B2200 Cat and tranny question

I have a 90 B2200 w/carb,auto and 200K mi.
The truck has two catalytic converters. One is just below the exhaust manifold and the other is under the truck -- both look original. The front one rattles and the truck has a definite drop in power lately. So I believe it is time to replace the converters. Why does the truck use two converters ?? Is the interior catalyst different for each one ?? Can I just use one converter and get rid of the front converter ?? This state (NC) requires sniffer test and visual so I can not just ditch them.

Standing in front of the truck looking down at the bottom of the radiator are the two lines coming from the transmission. Which line is the return line -- the left or right line ?? I want to add a transmission cooler.

Thanks

i would bust out the frist one and leave the shell in there you should be able to pass the test like that but then again i live in TN were there is no test but i think you will still pass if everything eles is in good shape

i'm sorry this has nothing to do with the post.. but where in NC?
Mike