If I recall correctly, your bumpers can only be 39" above the ground, and there's another spec for maximum headlight height. I cant remember what it is, though.
As for engine swaps, I'm pretty sure it simply depends on the county where you register the truck. If they dont do emissions testing, nobody really cares. If they do test, then I think you have to comply with all emissions requirements for the year the vehicle was built. I cant say for sure, never had to test my trucks.
As for being from another state- sort of. If you keep the truck registered and tagged there, then their rules apply. If you intend to register it in TN though, you have to comply with the State of Tennessee's laws, regardless of compliance with any other state.
A forum community dedicated to Diesel engine owners and enthusiasts. Come join the discussion about performance, builds, ecodiesel, towing capacity, modifications, classifieds, troubleshooting, maintenance, and more!