Rodney's response is not even close to being 100% accurte. The smoke screw has nothing to do with "hot rodding" it deal with driveability issues. It also does not add any more fuel to the engine nor does it raise EGTs. The same amount of fuel is being injected, albeit at a faster rate than stock. The full power screw adds teh fuel, and even with a half a turn of my fuel screw, my EGTs max out at 900* with the factory craptacular exhaust straight piped. My 2wd can go a lot of places. A lot will depend on your local driving conditions and what you're going to do with the truck. I've taken my Dodge across cattle pastures and through washouts and never spun a wheel. The trannie problems are not nearly as dramatic as some may seem to believe. My Getrag is a reman unit that was replaced way before I bought the truck. If you fill the rag like you're supposed to (overfill by 1qt. preferred) then you'll be fine. Don't drive it like it's a race car...the Rag does not respond well to speed shifting. The autos are marginal in stock form but they can be upgraded or replaced very easily. And bigger exhaust does not mean that the truck was rode hard at all, nor does the idea that if it's not shop installed the owner doesn't give a poop. It helps with EGTs if you've tuned your VE pump, it increases fuel economy, faster turbo spool, and sweet sounds. I've personally modded teh exhaust on all my diesels except my '00 Cummins which had a glasspack welded in. I bolted in the MBRP setup myself.
Now for a real answer. The truck is worth 1900. The motor alone would be worth 1500 plus whatever else of the truck is in good shape if you had to part it out. A Stan's 4" exhaust is about $350 right now for perspective. Rust is all about perspective. My truck as rust from the worn off paint. If it's structural that's a little more problematic, but for you that may not be a big deal. If the truck is worth 1900 to you then that's what it's worth. After all the real value of teh truck is what the market will pay for it.