distrbutor click noise 350

I have a 1993 GM grand sierra 5.7l/350 2wd excab with 255000 trouble free km. Despite being partially deaf I noticed a clicking noise coming from the engine that I took to be valve related. Pulled the driver side valve cover and checked the rockers and found nothing backed off. The neighbour came by and said he thought the noise was coming from the distributor. Since the noise appears to be half time to the engine that made some sense and a listen with a stethoscope confirmed it. Haven't had time to go in to it yet but when I do what am I going to find????

Is it fuel injectors clicking? All Distributers are is a shaft with a gear.

With that kind of mileage I'm assuming the cap and rotor have been replaced at least once. I'd just look under the cap and see if you've got some carbon scoring or if the electrodes are burned down. It could be arcing and melting the plastic somewhere. If anything looks melted or charred, it's cheap to replace the cap and rotor.

clicking noise from distributor is cap hiting the electrodes in the cap... upper shaft bearing/plactic bushing is worn. replace the distributor(200$) and prob will go away. had same.