posi vs. limited slip

I would recommend a Detroit Locker but since you don't want anything that ratchets around corners, I am going to recommend a limited slip.

I have a True-Trac locker in my 66. All gears and no noise. I love it so far!

Lockers are locked until youy go around a corner then they unlock and ratchet (Detroit Locker) or similar (powerTrax No-slip). A posi-traction (Chevy term) or limited-slip (Ford term) are torque sensing differentials. They are basically open (only one axle engaged) until slippage is "sensed" at which point the other axle is engaged (now both are engaged). Since only one axle is typically enagaged there is no need to disengage (ratchet) when cornering. Said another way, a locker has both axles engaged unless you're cornering, and a torque sensing diff only engages both axles when there is slippage of the one axle that is engaged.

I have a TrueTrac and it seems fine, so far. No clutches and it's torque sensing. These are a favorite of corner carvers (TrueTrac or Torsen is often used). There are enough clutchless limited slips now that you needn't use a clutch/cone-based diff. I'd say PowerTrax for a car with mostly straight-line acceleration in mind and True Trac for everything else on the street.

I second the TrueTrac because after research and advice, I have decided to go that route.

Tyler