The original timing gear would have nylon teeth, aftermarket gears would be steel. GM used nylon gears to reduce the noise on the timing chain, they started with those in the early V8's (60's) and continued for most of the Gen 1 small block run. Your engine should have stamped numbers on the block just in front of the passenger side head. That number will give you the build date and designation (car or truck).
Last edited by TUTS 59; 08/09/2021 4:04 PM.
