This topic has been asked a million times, I shall break this down and hopefully this will be the "go to" thread on this question that arises quite often.
300A's were the first issue of Marauders they were all black and had the following equipment...
Auto release fuel door
In-dash Clock
Map pockets in the front seats
Full size spare
Auto Release Parking brake
Windshield tint
Hood light
4R70W Transmission
Single engine knock sensor
Black Valve covers
2400 Stall convertor
Only options for the early 300A's were a trunk organizer, rear spoiler, and a 6 Disc CD changer.
300B's came out mid year and were offered in black, silver and dark blue pearl. They had less features then the 300A so they are considered "Decontented"
Differences on the 300B are...
Heated seats
Traction control
Manual fuel door
Mini Spare
Dot Matrix on upper portion of windshield
No map pockets
Clock in radio
No Hood Light
Options for the 2003 300B's and all 2004 Marauders were a 6 Disc CD changer, rear spoiler, sunroof, and trunk organizer.
Some mid production year Marauders have been found to have a little bit of the 300A and 300B features combined.
2004 Marauders were offered in black, silver, and dark torador red which replaced dark blue pearl. New additions for the 2004 were the 4R75W transmission with stronger internals and torque convertor with most likely the same stall speed of the 2003. The Black valve covers were dropped and plain aluminum were used instead. The 04 was also given dual knock sensors.
2004's were offered in 300A but all features were those of a 300B.