Thanks to Dave and Cecil. There is about 40,000 miles on the rebuilt motor. The oil is changed every 1000 miles and there is no sludge on the head or in the pan when I pulled it last year. I blew a head gasket a few years back and after putting it all together is when the noise started. When the motor warms up the sound is almost impossible to hear. However when the outside temperature is around 35-45 degrees or the truck has not been driven in a few days, the clicking is very loud. The truck does run smoothly throughout this time however.
