Do y'all realize the F-15 is 51 years old? That is, since its first flight in 1972.
So we built the F-22, once again tried to stuff multiple missions in one airplane, with Stealth added, and now we are buying more F-15's. Have we ever done that before?
Note we are still building F-16's as well, and it is only about 4 years newer than the F-15.
But we were not still building any of them in 1990.
I guess the C-130 probably has the longest production run of any US military aircraft. They are still building versions of the J-3 Cub, although mainly homebuilts, and versions of the Ercoupe went into production in 1940 and the last ones were built around 1970. Beech Bonanzas were built for an even longer period.