[r0nin89]

My vote would be a 9in just for ease of the third member. Thirdmember rears are really nice to work on and dont need any kits to eliminate c-clips.

Also I kinda speak from a truck perspective here but a d60 isnt too much stronger (stock vrs stock) than an 8.5 10bolt. As said though its apples and oranges when your talking about built to the nines and not.

If ya really want something bullet proof get a 10.5 Corp 14b Full Floater LOL will make the tiny bit of drivetrain loss your comparing amongst those rears seem like nothing.

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On the locker, vs spool, vs posi note.

Coming from someone whos driven with a locker on the street daily in his truck I cant recommend it for a stick vehicle. You have to half clutch around turns other wise the ratcheting will bang.

This is another advantage of the 9in... Setup a third with some DEEP gears and a spool for when your at the track. 8 bolts slide the shafts, unbolt pumpkin, and put in the track pumpkin. All in all its an hour spent for track prep that can make your car much more streetable than trying to find a happy medium.