Max pax numbers for the F50 is listed as 62 as per AOM Weight and Balance Section. When the aircraft is configured with more than 50 seats, the front LH wardrobe is removed and the RH front Cargo compartment is smaller. This allows an extra row of seats. The galley is smaller, which allows another 2 seats. Seat pitch is still 32".
The aircraft XR got from Ansett have the larger 'Altas' galley that were bulit just for Ansett. Looking at the S/N's for the Alliance aircraft, it appears they have the higher MTOW of 20820 kg.