You will be hard-pressed to find one. It would appear that USO had some design flaws and are replacing a lot of customer's levels. It would also appear that they can't keep up with the volume of replacements as well as new orders. I'm not sure if the replacements are any better/worse. I sent USO an email asking for the projected availability date, but haven't heard back from them."Way2evl"U.S. Optics Swivel. Pricey, but the best if you have picatinny rail.
That one looks pretty nice with a low price."scubajeeper"Check these out, I have two, they are well made and the price is right.
https://www.amazon.com/gp/aw/d/B019FBBEWC/ref=mp_s_a_1_3?ie=UTF8&qid=1484592372&sr=8-3&pi=AC_SX236_SY340_QL65&keywords=scope+level&dpPl=1&dpID=41s4o2KRlIL&ref=plSrch
Depending on the scope manufacturer, some can't even properly align the reticle without cant. It would be really annoying if the bubble level inside the scope isn't perfectly aligned to the reticle."addertooth"Don't forget there are some scopes which have levels inside the tube. You can view your level without moving your face from ideal cheek weld and in context with viewing your image at the same time.