I have a '98 Sonoma with the 4.3 V6. It has 143k miles on it, and I
have never had any problems with it. In the past couiple weeks
though, I heard a tapping noise like metal against metal when
accelerating from a standstill. Now there's not just the tapping, but
the whole truck vibrates and shakes whenever I accelerate even at high
speeds. The tapping and the vibrating sound like they're coming from
the bed right behind the driver's seat. Has anyone ever had this
happen before or have any idea what's going on?