About the last two out of 3 times when I turn off my truck and get out, I hear a ticking noise, coming from under truck maybe around rear axle. It's a consistant rate (approx. 2/sec as a guess) for maybe 15 seconds. Then it stops. What is it?

???hot exhaust cooling off???

:exactly: mine does

I'm not saying anybody is wrong, but I don't think it's anything to do with the exhaust.

Which side?
Mine makes some loud a$$ popping noises as it cools off.

Sounds like it's coming from driver's side. I am not sure if it will happen with both the truck running and turned off, but I notice it as soon as I opem ny door.

The only thing I could think of, and this is totally just a wild guess, is something to do with the fuel pump, or transfer pump between tanks maybe.

The "Ticks" are consistantly paced, the last one is just as loud as the first (not LOUD), and it stops just as quickly as it starts. Since it does it as soon as I open the door and due to it's constant timing, I don't think it is the exhaust cooling.

If it matters, I've been hooked to a GN for the last week or so. I am not sure if it will do it with just the truck.

I noticed it doing it today when I cranked up. Could it be the fuel pump?

its funny you mentioned this. The old ladies' 2006 Saturn does this exact same thing. perfectly spaced 2 seconds apart ticks.

I've also noticed the vehicle does it while running. Since there really are no interchangeable parts between the two its weird and an interesting coincidence.

Doesn't the cab/chassis have a transfer pump between the tanks? That would be my guess.