Thank you for digging and finding that.

Tier 1 prior to 1999 covers a lot of inexpensive used light duty trucks.

Looking at the prices of todays pickups, the need for urea emissions fluid, plus the Tier 2+ fuel economy hit... I think I would prefer to buy a $3000 used truck from a low rust section of the country, put $5000 to $8000 into fixing it up, and another $10,000 putting this engine in it.

Comparing that cost to the $40,000+ price of today’s new pickups
with their scads of questionable durability electronics,
it seems like a better value.

Unfortunately the 25% better fuel economy over gasoline gets partially eaten up by the higher cost of ULSD fuel.