I had a 98 monte carlo, same engine. The 3.8 is a good engine, I got close to 30 mpg on the highway and it had 200+ hp. The 3.4 I'm not sure about, the 3.1 had intake gasket issues. Since the 3.4 is basically a bigger 3.1 I'm iffy on that engine. Every single GM W-Body, like the impala, will have transmission issues around 80k, that is why I got rid of mine. If you are comfortable swapping one yourself a used or rebuilt one is about $1000 or so. I'd have an Impala myself instead of the trac if I could fit in it, with the new design I have issues with how far I need to recline in order to see out the windshield comfortably.
If you do get one and want to buy a full-sized 16" spare, 16" steel wheel, or the police center caps for it drop me a line, I still have parts left over from when I had the MC.