Can't tell from the pictures I found exactly what shape the FS3000 uses, from what I can see they appear to be typical oval side marker lights. You should be able to find a replacement by searching for "LED side marker lights" on etrailer.com or amazon.com both have a fairly wide variety.
2018 Forrest River Salem Hemisphere 282RK - 2017 RAM 1500 TV
Previous RVs and TOADS
2004 Fleetwood Bounder 32W on WH W20
2000 Four Winds 5000 21RB
1986 27' Allegro
TOADS
2005 Ford Ranger XLT 2WD
2004 Suzuki Aerio
1988 Chevrolet Sprint