Depending on $$$
I would plan on swapping some parts while your into it, are you haveing the trans rebuilt somewhere? anyways I hate..I hate ..I hate swapping tranns in and out, in the last 1.5 years I have had to swap 5 on one truck, thats simply crazy.
spend the money on a new tourque converter, if you are having a shop do the rebuild do your homework on their reputation and abilities, and let them know what you exspect it to do. go to harbor freight "40.00" or some hardware store and spend some money for a large high reach jack, or check the classifieds or craigslist in your area for a used one.
as for the exhaust, some people have talked about the kit from lmc, the price was damn nice and a clean non cobbled up exaust is something to be happy about, if your under there do it once and do it right.
the t-case, some have drains, you should have to use a wrench or a rachet to take out the plug, depends on the case but the manual should say under the maint. section.
also just a note, I cant remember which one it is but I prefer the permatex white gasket sealer, and since you are going to be fluid happy do your diffs while your at it, it might need attention and at the very least you can see if there are metal shavings or some upcomming part failure lol also get some locktight and apply where needed!since the drive shaft is out, get some new decent u-joints, a hammer, some pliers and a socket and learn how to swap them, they may need it anyways and doing it on your bench is alot better then calling a friend to bring you one and fixing it on a nice icy cold day in the snow..
safety is important with that much weight, just take your time and do things right, if it takes a little more money or time then so be it, just do it right and you will have less headache afterwards.