I got the Preload adjuster (for 3/8" drive).
I am off on a trip until Monday, so can't actually try it right now.
The 3/8 square hole is close to the edge of the metal and the ratchet will hit the shock body if you don't use an extension. No room above the collar...
BUT, maybe I can use a long extension from below. I think this will work. The next question is whether the curve works on this shock. I think it will allow maybe 1/4 turn or less per move. I will use my breaker bar if possible.