Ticking Noise?

[quentin hill]

I have a 72 C-10 and recently it has developed a ticking noise. When you first start driving it it's not appearent then after about 20 min when I am coming back into the neighborhood you can hear it.

I have replaced the wheel bearings and it's still there.
I have checked the flex plate for cracks and no cracks.
I have shook the drive shaft and all the u-joints are tight.
The speedometer does not bounce like it's broke.
I have looked all over the truck and nothing is rubbing so I just do not know what the heck it is.
I do not think it is coming from the motor or the exhaust since you cannot hear it while the motor is idling or when you rev it up.

Any ideas or sugestions would greatly be appreciated since I do not have the money right now to take it to the shop. The IRS took it all

Thanks for your time.