As far as I know, the only front loader Ford makes is the 9". If it has a removable third member, it is most likely a 9". To check if it is a posi unit, rotate one axle by hand and watch the other. If the other axle turns in the opposite direction from your perspective, it is an open diff.
1992 Ford Bronco
E4OD- B&M Stage 2 shift kit
Full 3" stainless Bassani Exhaust
32" BFG's/stock suspension
"No replacement for displacement."
"Our lugnuts require more torque than most Honda's produce!"