Try I have dealt with both and have had great service.
https://www.pplmotorhomes.com/rv-parts-rv-accessories
or
https://www.etrailer.com/maindept-RVandCamper.aspx
2015 F350 FX4 SRW 6.7 Crew, longbed - 2017 Durango Gold 353RKT
2006 F350 SRW 6.0 crew longbed sold
2000 F250 SRW 7.3 extended longbed airbags sold
2001 Western Star 4900EX sold
Jayco Eagle 30.5BHLT sold, Layton 24.5LT sold