Beginning with the 1994 issue (released in 1993), Indiana finally went to a five-year plate replacement cycle for trucks.
The only downside to this is that truck plates tend to get the living daylights beaten out of them, so after five years, they're sometimes pretty rough-looking.
Style notes to mention: The state name resembles that used on the 1994-98 "Amber Waves of Grain" plate.
Beginning with the 2004-08 issue, truck plates began to follow their passenger counterparts in going flat, although most early plates were still stamped. My gut feeling is that it's going to be very difficult to find flat truck plates that are worth saving after five years. They're so thin and flimsy that I can't imagine them holding up that long.