what year truck bed will fit my 1999 silverado 1500 8 foot bed

In 99 Chevy made two body styles, they had the early style which was basically a 98 because they had left over inventory but later 99’s was the newer style , so I’m assuming you have the later style , (body style that introduced the 5.3 vortec) this body style ran from late 99 to early 04 (04 was the switch to the more aggressive front end) so I’d say you’re safe going late 99 to early 04 (or late 03 if you order one) now if you have a early 99 (last year of the 5.7 350) that tail gate is the same from 88- early 99 with exception of the sport side, but the fleet side bed is the same . I hope this helps :) Check out my brand new ride!! It’s my 5th Silverado and my dream truck!! LOVE THE BOWTIE