Exterior dryer vent cap

I did a full cleaning on my dryer duct work earlier today. I used the lint eater kit.(Purchased on amazon) I have around 20 ft of duct that runs through the floor and elbows in my crawl space to outside. I removed the outside dryer vent cap to clean the system and noticed the builders installed the duct work at an angle through the concrete blocks/foundation, instead of level. Well the top of the duct sticks out more than the bottom(see attached pic). That explains why the dryer vent cap damper wasnt closing before I took it off( I was figuring it was because of lint buildup). After cleaning I temporay reseated the vent cap. I could get the damper door to shut all the way but it was on angle with the floor duct so wasnt flush against the blocks/foundation. It looked sloppy. So I am looking at what to replace it with. Any ideas what I can do in this situation? I dont live in a very cold climate(south tennesse), but was hoping to use the damper just to save on power and to keep the small pest/insects out when dryer isnt in use.

Also the current dryer vent cap is the aluminum type. To reinstall it I have to put over the existing duct, it folds over the inside of the dryer vent cap to secure it to the duct, which will probaly be a pain in the but to reinstall. To take it off I had to unfold the end of the duct to slide it off. If you look closely at the pic you can see where it was folded on the ends of the ducts coming out of the blocks/foundation.

 

I have an exhaust vent cap that has a series of small louvers. They swing open with the dryer is running but close as a damper when the dryer is off. The louvers are vinyl and easily removed to clean the vent.

 

This is what PD is referring to:

https://www.homedepot.com/p/Whirlpoo...B&gclsrc=aw.ds