Monkey said:yes, the axles are interchangable (as long as you have a pre-99). both are 28 spline and same length. if you have a 99+, then that rear end is 1.5" shorter than your current rearend. just put your axle housings on the pumpkin and youll be fine.
like corey said, as long as the posi is in good condition, dont spend the money to get a new one