This is the 4¢ Stagecoach coil issue from the Transportation series. Although these stamps look similar, there is an easy way to tell them apart.
Scott #1898A was issued in 1982. The inscription across the top, “Stagecoach 1890s” is 19.5 mm long. It spans almost the entire width of the stamp. There is only a little white space between the perforation holes and the start (or end) of the inscription.
The stamp was redrawn and issued again in 1986. This time, the inscription is only 17.75 mm long. It’s 1.75 mm shorter, which doesn’t sound like a lot. But when you compare these two issues side by side, the difference in noticeable. On #2228, there is more distance between the perforation holes and the start (or end) of the inscription.
Another thing I’ve noticed is that on mint copies, the paper used to print Scott #2228 is whiter in appearance than the paper used to print Scott #1898A. Of course, this isn’t as exact as measuring the inscription.
Both stamps are common. If you’re not careful though, it’s easy to mix them up because they look so similar.
For collectors of errors, be careful. Both issues are known imperforate. Scott #1898Ad is the imperf variety with a Scott catalog value of $625. Scott #2228b is the imperf variety on the later redrawn issue and has a Scott catalog of just $200. Because the perforation holes are missing, it’s important to measure the inscription. Make sure you’re buying a true #1898Ad, and not an imposter #2228b.