Start at X38 and hike to Dirty Harry's Peak. Then scramble on to Dirty Box, and then scramble to Mail Box. Then reverse course and return to X38. Class 2 to.Dirty Harry's. Past that, sources disagree, possibly class 2-3, possibly higher.
For beta on Dirty Box, see https://www.summitpost.org/dirtybox-peak/510698. It says that.there are multiple approaches, and we're looking at the SE approach which it says is mostly class 2 to 3.
Also see https://www.wta.org/go-hiking/hikes/dirtybox-peak. This suggests that it may be too dangerous to actually get to Dirty Box from Dirty Harry, and that getting to Dirty Box is usually done by starting from Mailbox, so proceed with caution and turn around if dangerous.