I have some good news and some potentially really bad news.
I spoke with the folks at the state's emissions board today, and apparently the swap that I did is illegal according to the EPA. They define a heavy duty truck as one with a GVWR of 8000 lbs or higher, and a light duty truck as one less than 8000. Apparently putting a heavy duty engine into a light duty truck is not legal because the emissions requirements were loosened a bit for the heavier vehicles.
After hearing that, I decided to stop dicking around with different emissions stations and just put the cat on from the donor truck. Took it in, passed emissions, and got the truck registered and plated through my local county office. That's the good news.
Bad news is that apparently all title corrections (I had to change the title from gas to diesel) go through the state for review. If they forward my change on to the emissions board for approval, they may want me to come in for an inspection, in which case I'm screwed. Clearly the lady at the county MVD office that I spoke to at the beginning of all of this didn't know what the hell she was talking about, which I guess shouldn't come across as too much of a surprise. Anyway, I guess it generally takes around 4 weeks before my updated title would come in the mail, so I'll be biting my fingernails for awhile hoping they don't send me to the emissions board.
This is the shitty part about trying to do this the right/legal way. My dad lives in a non emissions controlled county. I could have easily registered the truck under his name, not updated the title, not had to deal with emissions, and been fine...now that this process is started there's no turning back. If it goes well, that's great, if not, I'll have to see what they require...best case would be they would return the title to me and say sorry we can't update this, in which case it may still be possible to register it at my dad's address. Worst case is they will red flag it, and I'll have to convert back to a gas engine to be able to register it, or just say f*** it and sell it to someone out of state. We'll see.
Took it to the landfill today and weighed it. Their scale initially said 5760 lbs, but by the time I left it had creeped up to 5900. The guy said that it could fluctuate due to wind, up or down...so I'm just going to say 5800. This was without me, and with a half tank of fuel.