I think I might have found it guys! lol

https://www.strava.com/segments/518565

The only thing is it has flat parts that you can rest on for 2-3 seconds.

I ended up descending Marin avenue at the end of my ride on Sunday. I've already climbed Diablo + another 4000 feet that day but I was in awe of how steep the thing was going down so I turned around and climbed part of it. My legs just didn't have enough in them after 70 miles and 8000 feet to finish it but I'll be revisiting for sure!