Looks amazing!
Just an OCD thing, but should the side cylinders protrude a little further?
I think they do need to protrude a bit further. This image shows the side view from the movie, then Rusty's WIP sculpt, then the 3/4 view from the movie, and finally the HT sculpt.
Interestingly, I think I finally found what those cylinders on the side of the power droid/gonk are - a detail that seems to have evaded toy manufacturers since 1977, all the way up to HT today.
My guess is that the prop/costume was lost and LFL licensing has no better reference to offer to clarify it for sculptors.
Shown below is the back of another gonk seen on the Mos Eisley streets, so presumably a gonk built alongside the sandcrawler gonk in the same prop-maker shop, sourcing the same box of greeblies.
Side by side with the sandcrawler gonk up close, you can see in the pic below that pretty much all of the details line up (eg. the secondary bolt heads on the flange closer to the body and the squared bracket that supports the two sleeves can just be made out on the blurry sandcrawler gonk pic.)
So there is no "chain" (or "pearl string" as HT has sculpted) - what they are seeing is just two metal sleeves that accepted a cable/conduit protruding from the main cylinder. The sandcrawler gonk just seems to have two of these same cylindrical greeblies, the lower one rotated so that its sleeves line up with the sleeves of the upper cylinder. The two pairs of sleeves are what created the suggestion of a "chain."
Hopefully it's not too late for Rusty to tweak the sculpt to make this accurate - for the first time EVER.
(*note that the whitish blurry shape seen on the actual face of the cylinder appears to just be where a metallic compliance sticker was removed from the greeblie, which seems to be the base of a 1940s ship's passageway "cage" light, so I don't think that should be included because it's just discoloration, not a physical shape.)