i bought 5.63 sidekick front and rear third members and lucked into finding a already made hybrid axle.  just wondering if i have to use the samurai axles with the sidekick rear third member or do i have to use the sidekick axles with the sidekick third member.  i know to switch the front third member housing so it will be steel not aluminum and that everything in the front will work.

If I remember correctly, the Sammy and Kick side gears are the same thread count ( for the life of me I can not remember the proper name). In other words, when I put my TT hybrid rear in the back of my Sammy I had no problems with installing the Sammy axle shafts into the diff.

Spline is the word your looking for.
Samurai's use a 26 spline in the rear, and a 22 spline in the front.

With the Hybrid rear you use the Sammy rear axles with the Sidekick rear diff.  They both use the 26 spline.

As for the front diff, it depends on what year the gears are from.  If it is a 96 and up, you have a 26 spline front end.  You will need either heavy duty front axles (Calmini, Newfields, Trail Tough, ect.  Low Range Off-Road has a selection of them) or replace the side gears with the ones from your existing front diff.  If it's 89-95 you have a 22 spline front end and it can be swapped straight into the front.

Most people remove the gears and place them in a Steel carrier in order to avoid breaking the aluminum one.  I ran the aluminum carrier fine for a year, but switched to steel when I bought an ARB.  Kept breaking the Detroit EZ-Lock.  If you are going to get a front locker, go with the Track-Lock.