I am going to order a new rear housing as mine is cracked. I am going to be really pressed for time when i get it. How tough and how long of project is it swapping out the rear housing? Thank You

I assume you've heard about the "Pump rub" issue. If not, search "pump rub" and sit back and read.

Some have said to do this in 5-8 hours. You could install a T-case pump rub up-grade as long as you're at it. Merchant or Kennedy Diesel sells them.
http://www.merchant-automotive.com/transfercasepumpupgradekit.aspx
http://www.kennedydiesel.com/categoryresults3.cfm?Category=11&SubCategory=109&SubCategory2=135
Here's the rear case half:
http://www.merchant-automotive.com/263xhd261xhdrearhousing.aspx
I believe you must remove T-Case from truck to replace the rear case half. This may be the only way to release the output shaft bearing from the case.
Merchant sells the up-grade kit which includes the needed T-Case to trans gasket, RTV gasket maker, and he has easy instructions on-line.
Here's very helpful info:
http://www.merchant-automotive.com/tech/tcp.pdf
http://www.dieselplace.com/forum/showthread.php?t=140732
If your mechanically inclined and have tools, with above instructions it's not too hard. If doing at home laying on back, a second person is helpful removing and installing T-Case, which weights about 75#. If installing the pump up-grade, a good pear of duckbill type snap-ring plyers is a must, (which I didn't have). The snap-ring holding the bearing in rear case wasn't too hard to undo, but the second snap-ring holding the bearing on output shaft was a bugger to remove without the right tool.

Great Info!! Thank You

Fantastic post, Modified.