Does anyone know if the camshaft gear on the 4.3 liter engine is plastic or metal. I have heard that some of them are plastic? I am debating on whether I should change the timing chain and gears. My truck has 147000 miles on it and it doesn't burn oil. Except for the valve guide seals. Any recommendations? I have heard to change it and I have heard to wait until I rebuild the engine to do it. I am not sure what to do because I am confident I will get at least 250,000 out of the engine. I don't know about the tranny. Let me know your thoughts on the timing chain. Thanks! Big Mac