does anyone know what posi came in the 4th gen F's?
I bought a rear end from someone and I cant decide if Im going to use it or the zexel from the new rear ends.
It has the speed sensor for the abs on the carrier inside the case. Any one know what year this is from or were they all like that?

You bought a rear end not an axle.

Fourth gens came with a 7.625" clutch style posi.

which works better? The posi from the fourth gen or the zexel posi from the new f-bodies?

Whenever 4th gens get the SLP upgrade installed they remove the original posi and replace it with the Zexel HD one.

The original posi units are then resold as the $99 SLP takeoff units.

The Zexel HD posi uses gears instead of clutches.

Gears will last longer than clutches, so compare for yourself. However there are other clutch type posi units (Eaton, Auburn) that arguably are just as good.

Well I thought both zexels were gears only. I should have bought an auburn instead. Then I could of kept my axles and saved a little $$

the zexel is what GM calls its torsen gear style rear ends, yes theyre nice for cruisin, but if u want big hp, and torque sick to the regular clutch packed posi's. often if u want to buy a diff for your car theyll ask what kinda hp u wanna put out and torsen arent the best for high horsepower