DaveInDenver said:
//snip// But here in Colorado I think diesel (and engine swaps in general) swaps into gasoline titled vehicles younger than 25 year becomes more hairy.
A few years ago (in CO) I was told that it isn't really too much of a problem, but the vehicle would have to meet the emissions standards for whichever is newer.
In other words, if you put an old engine in a new vehicle it would still have to meet the emissions standards for the year of the vehicle (naturally), but if you put a newer engine in an older vehicle, it would have to meet the emissions standards for the year of the engine.
So, if you wanted a newer engine you had to plan on catalytic converter, egr, smog pump, etc. for the year of the engine. (Legally, any way.)
Don't know if that's still the case, or even if it was gospel when I heard it...