Front unlocked would fit into a front unlocked but not into a front locker one unless you drill and tap a coulpe of studs and make sure thesealing area would seal, they are physically different (locked to unlocked).
As for the rear, the FJ 80 is a c-clip syyle rear end. So that said, physicaly they would fit, but would be weaker in design then the FZJ 80 with FF, How much weaker, well not a bunch. You would have to make sure you have all the spiders in and the center pin locked in place before you install it. Personally I would not do it, unless you are puting a different carrier in(arb. dertoit, etc), just using the housing.
The FJ-80 housing again would not fit into the rear of a locked axle unless you drilled and taped a couple of studs and make sure the sealing area is ok for this.
Both the front and rear locked housings and axles are different, the are enlarged where the locking mech are. Also have more studs and the studs are in different positions the the unlocked one. this is why I say you would need to make sure it seals well.
later robbie