differences in 98,99 and 2001 GTs...

99 35th aviversay car
00 pretty much the same just not an aniversary car
01 added hood scoop, sidescopes, diffent wing early models t-45 later modles 3650
02-04 ther is a maf change I do belive. the 04 is 40th aniversary

the romeo/windser I am not as up on. research that a bit. I dont' recoment just listening to anyone as many poeple just repeat what is read and don't really know the whole story. the infor is out there just do the searches.

ther are many people that have had issues with the 3650 tranny even though it is supposed to be more durable. I have the early years model with a t-45 it is still alive not shifting issures at all.

anyone who like an 96-98 great. but they are very gutless compared to a 99+ I dove a 98 in 01 when I bought and could not belive how little power the car had.

these cars are not torque monsters so if you get an auto it will not impress you at the track stock.

covertables are heavier so buying an auto vert is kind of a no-no if you like performace.
 
There are lots of little differences on the 99-04 models, there are the more major visible changes in the 99-00 vs 01-up (hood scoop, side scoop, improved cup holders, and double DIN stereo slot instead of a pair of single DIN slots) On the mechanical side there were some minor changes each year, plus the major change of the Windsor block being used in the 99 & 00 vs. the Romeo in the 01+. Some of the other more minor changes are, the water pump (different underdrive pullies), different manual transmission T45-T3650 mid year 01, change of MAF design to integrate IAT with MAF in 03 I think, change of tensioner/belt routing in 00 or 01, etc. There are several minor cosmetic changes over the years, seat back pockets, A/C vents, etc.