This is some basic info on the LS1 that i've gather from all of the internet and put into one list:

1998

1. Had differnet casting heads which had perimeter bolts and valve covers.
2. Ignition coils were mounted to the valve covers one at a time.
3. The water temp gauge actually works.
4. Only LS1 year to not have an oil life monitor
5. WS6s had single outlet exhaust (all others had duals)
6. Steering wheel controls were completely different part with indentations on the buttons, and were better built
7. Only year that Purple, Gold, and Green were available
8. Some very early Trans Ams came with LT1 style headrests (see my sig for pictures)
9. Rear hatch release was poorly designed and often caused problems releasing mechanism
10. Early model 98 Monsoon stereos didnt have capability to control 12-disc CD changer
11. 1998-1999 automatic transmission LS1s could be started in 1st gear even with the shifter in 2nd. Starting 2000, if you put the shifter in 2, it would start off in 2, even from a stop.
12. 1998-1999 LS1 cars had a smaller throttle body cam, which caused the throttle to open to WOT faster than 2000+ cars
13. 1998 cars had 28 lb fuel injectors from the factory
14. 1998-2000 cars had a larger cam than the 01-02 cars
15. 1998-1999 cars had more restrictive exhaust manifolds
16. 1998-2000 cars had an LS1 intake with EGR
17. 1998 and some early 1999 cars had blue outside rear view mirrors (Trans Am only)
18. 1998 only LS1 blocks had a much smaller cylinder sleeve that only tolerated a .005" hone
19. Last year F-body to use the old 15.5 gallon fuel tank.
20. Only year LS1 F-body to contain a gascap with a tether long enough to actually hang from the fuel door while open
21. Only year LS1 F-body to not contain the famous GM black box used in the event of an accident to record up to 5 seconds of pre-crash data
22. 1998 only cars had a different PCV system with the PCV valve located above the passenger side valve cover
23. 1998 only cars did not have an idle adjustment screw on the throttle body
24. 1998 cars have a completely different PCM from 99+ cars
25. A production shortage of F-body cams caused the use of a C5 cam to be installed in F-body LS1s for a very short time

1999

1. 1999-2000 cars switched to 26 lb fuel injectors
2. Cylinder heads and valve covers redesigned to have center bolts instead of perimeter bolts. Other than that, the heads were the same.
3. Redesigned cylinder sleeves that allowed for a small bore, up from .005" in 1998 models.
4. Midyear model change to a cheaper steering wheel audio control button without finger indentations, and cheaper built
5. 1999 cars continued the LS1 intake with EGR provisions
6. 1999 cars continued more restrictive exhaust manifolds and larger cam
7. Only year that Hugger Orange was available (Camaro only)
8. 30th Anniversary Trans Am available with special blue and white paint package and blue clear coated WS6 wheels
9. Switch to larger 16.8 gallon fuel tank to meet new emissions requirements.
10. Gascap tether was shorter and could no longer be used to hang on the gas door when open.
11. Company wide change added black boxes to record up to 5 seconds of data before a crash
12. Rear hatch release was redesigned with stiffer spring that released the hatch better
13. Water temp gauge was redesigned to work basically as a dummy gauge and only show an overheat condition.
14. An oil life monitor was added to all LS1s, thus changing the gauge cluster a little to show the oil life reset swtich
15. 1999-02 cars had a different PCV system with the valve located to the side of the intake manifold
16. Early production 1999 Trans Ams still had the blue outside mirrors, but a midyear change went to the non-tinted ones

2000

1. Redesigned exhaust manifolds for new emissions standard actually flowed better and created a little more HP.
2. 2000 continued use of LS1 Intake, EGR, smaller cam, and 26 lb fuel injectors
3. Added rear child seat safety hooks to interior per federal requirements
4. Very early run of WS6s had "salad shooter" style rims. A production change switched back to standard 5-spoke WS6 rims.
5. Camaros got redesigned 10-spoke base rims, and SSs came with new 10-spoke rim design
6. First year of Monterey Maple Metallic paint
7. Charcoal (grayish) interior was replaced with Ebony (almost black) leather interior
8. Cloth interior cars got new rainbow colored cloth patterns
9. Camaros only got the Pontiac steering wheel with optional audio controls
10. Throttle body cam was increased in size to slow the speed at which the car reaches WOT
11. Automatic transmission cars were reprogrammed to allow a car to start off in 2nd gear from a stop when the shift lever is put into 2.
12. The last year a WS6 Formula was offered
13. Starting 2000 intake lids contained a seperate breather filter

2001

1. A small percentage of 2001 and 2002 LS1s actually had LS6 blocks which had a different part number and a darker metal cast
2. Starting 2001, all LS1s came with an LS6 intake manifold without an EGR system
3. Advertised HP output was changed from 305 to 310 on base LS1s and from 320 to 325 on WS6s and SSs
4. 2001-02 cars have a smaller cam from the Vortec truck engines to increase low end torque
5. 2001-02 cars had 28 lb fuel injectors like the 98 cars (albeit different part numbers)
6. WS6 cars had a redesigned 5 spoke rim which was more wavy
7. WS6 cars got less suspension upgrades from a base Trans Am suspension than previous years
8. Manual transmission cars all came with the Z06 clutch

2002 - Last year of the F-body

1. 35th Annivesary edition of the Camaro, and Collectors Edition Trans Am available
2. 2002 LS1 head gaskets redesigned. The new ones are a pressed metal, as opposed to the graphite ones and are no longer specific to the side of the car theyre installed on
3. 2002 cars continued with the LS6 intake, 28 lb fuel inectors and smaller truck cam
4. 2002 continued the use of an LS6 block in some LS1 F-bodies
5. A factory supported optional 345 HP option could be ordered from SLP
6. Manual transmission cars continued use of the Z06 clutch
7. Some 2002 model F-bodies came with a revised rear view mirror that had the map light buttons on the bottom, rather than the front.

compiled by constrictor98ta (mike) from ls2.com