Great post guys, lots of info! If I may add a bit, when changing the plenum gasket you may as well just do a full tune-up and replace commonly wearing parts on these trucks. I'm looking at you water pump and timing "chain"! Always recommend a new dizzy cap, rotor, spark plugs and wires, a new front o2 sensor, a new catalytic convertor, a new water pump and a good double roller timing set. The o2 and cat are a good idea because if your plenum is blown, all the burning will foul your o2 and cause poor mileage (well poorer then usual LOL), and a clogged cat, as DD94 said, will lead to cracked heads if left long enough! Water pumps areknown to go in these and your just a few bolts more from pulling it so might as well. Then you're at the timing cover so may as well pull it and install a real chain in there. Stock ones stretch over time. Seafoam when done! My 2 cents.