Pends on what you are ordering.
99-01 4 bangers were 2.4 twin cam motors and 02-04 were 2.2 Ecotecs
I think the manifolds were different from 99-01 and 02-04 with the 3400's.
Radios were different in 02 and up. 01 and down used the older stlye Delcos
Rear disc brakes were an option in the later years
rear speakers grills were different in 99 than any other year
"Oldsmobile" was very small on the trunk lid in 99 and 00, it was large in 01,02,03 and 04
02 and up, the outside rear view mirrors were all black, no more body color
03 started using regular headlights for DRL's
01 was the last year of the cover on the center consloe for the cup holder
Newer Aleros had more pictures instead of words for warning lights engine caps etc.
