Yah Spec pretty much got it covered. The pony package was offered in Florida
only in 01 and 02, and then became available everywhere in 03 and 04. The 03's came with the GT hood/scoop, stampeding pony graphics, black mustang inserts regardless of color, and polished 16" wheels.
Some pony package options also came with the interior upgrade package with included the shifter ring (like the one in the bullitts), and the silver bezel around the a/c and radio.
In 04, the pony package was basically the same except it didn't have the stampeding pony graphics on the side.
All the years pony packages were just cosmetic upgrades, no performance upgrades.