I just finished replacing both of mine dump valves on our 1985 Sov. It was easyer than I figured that it would be.
1. Removed bumper 4 bolts.
2. Remove plastic hose holder, drill out 6 rivets.
3. Cut pipes to get some operating room.
4. Loosen claps on valves.
5. Twist and pull out slowly valve's with a piece pipe out the hole.
6 Remove adapters from the valve for easyer removal of valve.
The reason I did it myself was that our local dealer wanted $500 labor and $200 for parts. I can cut the $200 but the $500 was to high for 3 hours of work. It took me longer since I never did this job before.
Merry Chrismas to all and a Happy New Year.
Regards from Russell in sunny and cool Tucson Az.