Perhaps a lot of TCLers won't be familiar with this, but in Pennsylvania there are two registration options for truck owners. The normal thing is to register your pickup just like you would do with a passenger car, getting a normal license plate and no big deal. The other option is to register your truck as a "TRUCK"; if you do so, your license plate will say "TRUCK" at the bottom and your license plate number will start with "Y". Of course, big commercial trucks all have the "TRUCK" plates, but I've seen a lot of regular ol' pickup trucks with the T-tags too.
So I'm wondering what the difference is, and why someone would choose to register their pickup under a T-tag instead of the conventional tag?