Go to your local muffler shop. They have a book that shows how your exhaust needs to be. If your truck is around an 84 the book will show only one converter. Been there done it.
Will

Chrysler has never used pellet-type converters; those were GM's stupid idea.
That would make sense, because one of the products of catalytic reduction of NOx is O2, which is necessary for catalytic oxidation of HC and CO (and, as you mention, is why the reduction portion of a 3-way catalyst is ahead of the oxidation portion), but the small mini-converters found in many multiple-converter Chrysler systems of the late '70s through mid '80s are in fact oxidation catalysts, not reduction units. Their function is as you state: Fast light-off for control of cold-engine emissions.
Again, this is only true when comparing the enormous old GM pellet-type converters to the monolithic types that have always been used by Chrysler. Monolithic converters are available in a large range of sizes.

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