This listing is for (16) brand new rocker arm pivot balls and lock nuts from Elgin Industries. These are for rocker arm studs that are 7/16-inch diameter. NOT 3/8 inch. 

• Compatible with 1965-1990 big block Chevrolet and GMC V8 engines in passenger cars and light duty trucks
• Fitment includes: 
• .
  • 366 CID (6.0L) 1966-1990
  • 396 CID (6.5L) 1966-1970
  • 402 CID (6.6L) 1970-1972
  • 427 CID (7.0L) 1966-1990
  • 454 CID (7.4L) 1973-1990