First off, an auto locker (like the aussie) will have absolutely no effect on the truck when in 2wd. Since you don't use 4x4 on pavement, you won't notice it is there.
If you are set on manual hubs anyway, you will end up with a weaker front end. The advantage is that if you break a cv joint, you can unlock the axle and drive home. Again, you sacrifice strength and risk blowing the manual hub right of the wheel.
Lots of people have done this on rangers, some on explorers.
You will need the following;
98-00.5 ranger halfshafts, and wheel bearing/hub units, and AVM manual hubs. The halfshafts and wheel bearing/hubs can be used ones from a junker if you think they are in decent shape.
The problem is the hub design. It's not like the good old manual hubs you used to find that were harder to install (because they were designed better). You literally unclip the auto hub, pull it off, and snap the new one on. It's not held on by any nuts/bolts/screws, just friction clips. A TON of people with rangers have had problems where the hubs actually pop off from the torque while using 4x4. This is without a locker. So I imagine with the added stress of a locker they would be popping off left and right. If your wheel center has a big enough opening, you might be able to ghetto rig a hose clamp around the clips to keep it on...?
I had the AVM hubs on my 98 ranger and they worked okay for me, but I read of tons of people who had them fall off.
