Forgot to mention why I removed my, uh, heat riser, um choke stove, y'know that darn exhaust flapper-thingy....
My drivers side exhaust was in great condition -- but the pass. side was rusted all to heck. Coincidence? Maybe... but the heat riser got jettisoned. This was after years of daily short trips where things never got all the way heated up. I guessed that with the valve directing exhaust to the drivers side, the pass. side never warmed up enough to evaporate the moisture, leading to extra rust.