Pontiac Repair: Got a bad ticking noise, fly wheel, pickup 4x4

Question
I have a 1997 Gmc 1500 Pickup 4x4 with a 350 Vortec motor. When you start it it has a a ticking sound which sounds like a lifter knocking, but it is coming from the torque converter area. I just had the transmission rebuilt 6 months ago. I checked all the bolts in the Fly wheel through the inspection cover and all were tight. Could the torque converter be bad? Could the fly wheel be cracked. Could there be a bad bearing in the lower end of the motor. The strange thing is the noise is only there at a idle or low rpm, It goes away when your going down the road. I have heard it when I've pulled my trailer and the motor is under a load. All of the fluids are staying at the right levels. Any ideas would be very helpful because I'm very baffled as what it could be.
Thanks for your time
Cory

Answer
Hi Cory:

does the noise go away once the truck warms up or does it quiet down? does the noise go away if the truck is in gear. If the noise changes or goes away when the truck is in gear then I would look at a tranmission issue. If the noise doesn't change at all hot/cold or in gear I would look at the engine as the root cause of the noise possibly a fly wheel but usually they sound worse when they are in gear. Is the nosie about 1/2 the speed of the engine speed if so that is valve train related. If not then look at lower end like a main bearing noise.  Good luck :)