Factory posi unit for a 8.5 axle. Had 3.73 gears on it. $150 plus shipping. The unit itself weighs about 24 lbs. so take that into consideration. If you bought a 442, Ttype, or a GN and it has the 8.5 axle, but no posi, this is for you. (It happens) I switched to a spool since I don't street...