I have a 69 Dart stroked Magnum small block 11.50 in quarter mile. I have a 8 1/4 rear with 4:10 gears. Hoosier slicks. 727 auto, 4k stall. Launch with no slippage. Car launches hard. The only mod other than gear ratio. Is an aluminum carrier bearing braced dif cover. Hundreds of drag strip launches. Rearend is fine. I have zero worries about abusing the rearend. But I do have a narrowed 8 3/4 ready if needed.