Review on Dorman 800-409 HVAC Heater Hose Connector - Ideal for Compatible Models by Danny Rogers

Says it doesn't fit my 2005 Chevy Silverado 2500HD LS with 6.0 petrol engine. I bought 2, notwithstanding the other comments here, and both fit the inner/outer heater hose quick connect line that comes out of the firewall. It may not look like it will last long, but that's because the o-ring is new. Apply a thin, light coat of lube around the pipe coming out of the wall of fire and it'll slide right off after trying to keep it dry. I put this exact fitting on both of my pipes and there are NO leaks. I highly recommend this as you can get 2 for the price of 1 Delco AC quick connector.