I remember the sound of a 409 pulling under load also, deep and throaty. Its very similar to a 427. Unless you're having problems with your current air compressor (pumping oil) you shouldn't need one soon. What I would look out for....
-Accessory brackets on the motor, (air comp., A/C comp., alternator, P/S) make sure none are broke and that all are tight.
-Drain oil and moisture from air tanks. Oil gums up air valves and deteriorates air chamber diaphragms. Water can freeze. With the truck at full operating temperature, shut the motor off, open air tank drain cock valves and let all pressure out. After the truck has been setting for about a half hour restart engine with drain cocks still open and let the compressor push out the remaining oil/moisture.
-If you have air leaking from a dual air chamber DO NOT try to take it apart unless you know what to do. They're spring loaded and very dangerous. Don't unscrew the clamp thinking its a simple fix, it can seriously hurt you.
-Keep up with the usual oil changes and tune ups.
Again you have a sharp looking truck, wish it were mine.
James
