There is a break in gear sizes on the carriers. From a certain size down will fit one carrier and s certain size up will fit another carrier and they will not interchange.
But worse case you should know now what your posi carrier will accept by what it won't accept ( gears off your open carrier) you could just get a new ring and pinion for the posi or sell ( they go fast on here)the posi.
So do you know what size gear was on the posi unit before ??
What size gear was on the open carrier.
