The Performer RPM Olds head 350-60517 is designed to replace all O.E. 1965-1976 400, 425 and 455 c.i.d. Oldsmoble heads, except 1968-1969 W-30 heads. It has all the performance features of Edelbrock's Performer RPM Olds heads 350-60519 except it is not port matched or bowl blended, making it legal for NHRA and Super Stock classes. It can be identified by the NHRA logo on both ends.