Richmond Ring & Pinion Set - 3.90 Ratio, 39-10 Teeth, GM 12 Bolt R07C09YS 640 in Max Width

640 in Max Width

1978-1981 Pontiac Catalina

1975-1977 Oldsmobile Starfire

6 AN Male to 1/4 NPSM Male

This alternator is interchangeable with GM # 10480326

Richmond Ring & Pinion Set - 3.90 Ratio, 39-10 Teeth, GM 12 Bolt R07C09YS 640 in Max WidthRICHMOND is the leading manufacturer of professional quality, hi performance ring and pinion sets. For over 80 years, the Double Diamond has signified the highest quality gears in the racing industry! GM 12 Bolt Installation Notes: When replacing a 2. 73 3. 90 ratio with a Richmond Hi Performance Ring & Pinion, the carrier must be replaced with a carrier from a stock 4. 10, 4. 56 or 4. 88 ratio. When installing 5. 14 to 6. 14 ring & pinion sets,