David,
Installing spools will mean doing complete diff rebuilds, similar to having your gears swapped, or even going to different carriers.
If you have never done this particular type of work and don't have the proper tools, you can ruin good gears and new bearings very quickly.
As mentioned by Bully, a spool in the front is never a good idea, if you have ever been in a truck with a front detroit locker, you will know what
he means. Even with a locker (which will un lock somewhat for cornering) they are very difficult to turn even small course corrections can over power a normal p/steering unit.