My buddy has been told that this unit has gone out. Cost around 100 bucks. Anyone familar with replacing these. Is it an easy job? Any special tools etc required Thanks in advance.

yo,
Assuming you ref. to the motor; Take a look at what Ric did:
Transfer Case, Borg Warner 1356 Electric Shift Motor Troubleshooting & Repair by Richard C (Bigric, Money Pit) at FSB Forums fullsizebronco.com
http://fullsizebronco.com/forum/showthread.php?t=30512