Hello I have a 2001 Chevy 2500HD 4x4 with approx 160,000 miles on her.  It's a truck that I've wanted for a long time but do to the cost of a new one I had to opted for a used  with some miles on her.  The truck is in great shape and so far runs like new.  My question is with proper maintanence and normal use how much more life could I expect out of her before she needs an overhaul.  

That is a tuff question to answer accurately. If you do not abuse it or run it hard when engine is cold and change oil often (every 3K or so) 200 to 300K is quite possible. As engines get older oil needs to be changed more often as it gets dirtier sooner. Many change oil less in older engine when they start adding to it and this hastens its demise. Watch engine temps too as hi temps are hard on engine and seals so keep cooling system in tip top shape. Also change tranny fluid and filter every 20 to 30K and watch tranny temps. Keep tranny below 210 and it will have a long life too.Tranny temps of 230 and above can shorten it life a lot and 250 and above can be really damaging. Do not forget to change axle lubes and Tcase lubes every 20 to 30K too.  

SnoMan
Thanks for the info, will do as to what you recommended.  

Like Sno said, with proper maintenance you can expect a long and happy life from your engine. But also remember that freak things happen, and with age the likely hood of those things is greater.