My truck is a 1998 and the year chose stops at 1999?

That is actually kind of funny. What site are you using because a 98 is definitely not a classic?

When i set up my listing under year of truck it asked for the year of it from a 1999 through 2020. It did not include (1998) or older, I selected 1999 and in the description of truck section I put 1998, so now when people see my ad it shows a 1999 and a1998.

Before 1999 the Silverado was not a model. It was an option package. Hope that helps! Jim