[Mr70]

That's the yellow <span style="text-decoration: underline">driven gear</span> with 24 teeth used on:
*1965-66 Impala series w/4:10 axle
*1965-66 Chevelle w/3:70 or 3:73 axle.
*1966 Chevy II w/3:55 axle.
*1967 Chevelle w/M/T AND either 3:70,3:73 or 4:56 axle.
*1967 Chevy II w/3:73 axle.
*1967 Camaro w/M/T AND either 3:73 or 4:56 axle.
*1967 Impala w/M/T and 4:10 axle.