Outer Limits 4x4 Board

Looking for help with a dilemma. Heard about a mod for the np205 Tcase to allow selectable front, 4 or rear drive and thought "sounds too easy" so i pulled my 83 1lt case apart. Looks like the o/p shaft needs replacing to accomplish this.
any ideas anyone??

are u talking 'bout a driveshaft disconnect?

never heard of them, the mod i was chasing was an internal one.
how do the disconnects work and how do they fit up?