Amtrak has also painted heritage units that represent their former paint schemes. As of 2021, Amtrak has several heritage units and special painted units. Currently I am only in the range of catching the P42 heritage and special interest units, but I hope to see a wider variety in the future.
Live Roster of Amtrak Units of Interest: https://docs.google.com/spreadsheets/d/1qCRTBkIxKQJz6AEQav6aPJubmkuiTT6DrZM_sXpiSME/edit?usp=sharing
A "*" indicates that the locomotive has been caught leading a train.
Amtrak 161 Phase I (GE P42DC)*
Amtrak 130 Phase II (GE P42DC)*
Amtrak 160 Dash 8 Phase III (GE P42DC)*
Amtrak 184 Phase IV (GE P42DC)*
Amtrak 46 Phase V Connecting America for 50 Years (GE P42DC)
Amtrak 100 Midnight Blue (GE P42DC)
Amtrak 157 Big Game Train (GE P42DC)*
Amtrak 189 (Former Big Game Train Unit; I saw this unit just after the stickers were removed) (GE P42DC)*
Amtrak 203 Operation Lifesaver (GE P42DC)*
The Amtrak 161, Phase I heritage unit leads a southbound Amtrak 97 (Silver Meteor) past Palatka, FL approaching the station.
Amtrak 130 (Phase II heritage unit) leads a late AMTK 91 - Silver Star southbound through Intercession City, Florida.
The Amtrak Dash 8 Phase III heritage unit, also dubbed the Pepsi can scheme, leads Amtrak 97 - Silver Meteor southbound out of the station in DeLand, FL.
Amtrak 184 Phase IV heritage unit leads AMTK 92 - Silver Star northbound out of the Kissimmee Amtrak & SunRail station in Kissimmee, FL.
The Amtrak Phase V & 50th Anniversary heritage unit trails on AMTK 97 - Silver Meteor in Palatka, FL. I personally count this as a heritage unit since the Phase V scheme may be phased out.
The Amtrak 100 Midnight Blue scheme special interest unit trails on AMTK 97 - Silver Meteor past DeLand, Florida on the day before Chrismas Eve.
Amtrak 157 "Big Game Train" leads AMTK 97 - Silver Meteor southbound past Lake Mary, FL. The Amtrak 189 was second out, which is a former Big Game Train locomotive itself, though the stickers were recently removed.
Amtrak P42DC 189 leads AMTK 98 - Silver Meteor just North of the Winter Park station in Florida. If you look closely, you can see where the Big Game Train logo used to be just behind the Amtrak symbol.