I am a long-time RV owner, and pretty mechanically inclined. But I have never owned a diesel vehicle. We are in the market for a used 34" MAXIMUM LENGTH diesel pusher. We want ample torque to be able to get the rig and our 5K toad up any hills; so the Tiffin Allegro Breeze is not an option. Due to the economy, the options for the 2008-2016 years are pretty slim. Due to environmental regulations, the options for 2008+ seem to have severely reduced torque. So, we have been looking at 2002-2007 RV's. A 12+ year old gas RV with 80K+ miles is not something I would consider. So my questions are these: Is a 12+ year old RV with a Cummins/Cat diesel on a Freighliner Chassis, and lets say, <100K miles, something that would be mechanically problematic? What is the expected lifespan of a diesel pusher engine/trans/chassis? How can I test or determine if the engine and trans are in good condition? Anything I should be looking for, or to avoid? If you have any thoughts on my situation or reasoning, please let me know. Thank you for your time.