hey every body! i'm gonna turn my DD durango into my tow rig and i would like some advice on what all needs done to build it into a really stout rig. heres what i have to work with...
'03 durango
4.7L engine
stock OD auotmatic tranny
stock t-case
stock axles and gears
currently running 245/85/16 M/T's (almost 31")
can anybody tell me where to find the specs on this drive train?  

You do not really needs the specs as factory tow ratings are greatly over stated. What is it you plan to tow and where as that determines what you may or may not need to do.  

well i want to tow my '73 chevy 6' bed on a 2,500LB trailer. and i live in a mountainous region. thanx sno man!!!! good to talk to you again!!  

Do you live at a high elevation and/or plan to tow to one too??  

i dont live very high no, but i would like to have the option to go cross country and then would encounter high elevations.  

Well you are pushing the envelope here with your tow vehicle. You are going to be towing between 7000 and 8000 lbs or about 1.5x the tow vehicle weight. Your 4.7 is not strong on torque due to limited displacement.If you were to install some 4.56 gears in your truck, power wise it should handle the load well, even in hills. A 4.10 would not be enough on long grades or at altitude with that rig in tow with your 4.7 and 31 inch rubber. Do not let the 4.56 scare you, you have OD and likely will be able to use it towing on flat ground under good conditions and all the time not towing. At 65 in drive with 4.56's your engine would be close to its torque peak  and will be making about 170HP at flywheel (based on gear ratio and engine RPM) and it would pull well on long grades and at altitude. Do this and seriously consider installing a bigger radiator with a small aux tranny cooler too and the only thing you are going to have to worry about is keep gas tank full at todays prices and not about being broken down with a blown tranny or cooked engine from towing. It is far easier to beef it to prevent failure rather than trying to do damage control when it fails miles for nowhere on a trip.  

thanx as always snoman!!! so i dont have to worry about axle strength at all?  

With 31's, the rear axle should be fine. I would use 85w140 in it towing though and not 80w90 or 75w90. 85w140 is a good severe duty gear lube.