Borg Warner made Spin Resistant (cone) differentials for many different rearends over the years. The 1959 ad in post # 45 does not show or mention anything about the 8.75" version, which was first installed by the factory in the 1969 model year.
1. Cone sure-grips were not installed by the factory in 742 cases.
2. Clutch sure-grips were not installed by the factory in 489 cases.
3. '69 and newer (model year) 741 cases came with cone sure-grips from the factory.
4. '68 and older (model year) 741 cases came with clutch sure-grips from the factory.
