That's the first I've heard of that. I was under the impression that all the 1 1/8" boxes were M22 thread pitch. When did you buy yours and did you have a whine issue?
I think I bought mine in 2014? I know they changed it to a slightly smaller unit not long after I purchased mine. I am still assembling mine, the only whine was more like a whimper when I looked at my checking account after I paid for it.