After two years of searching for a used drive , due to the largest gear having broken teeth ; the owner had his B-in-L build a new gear .
But then not everyone has a machinist in the family.
I told him as long as they were set up to make one , they should run off a few dozen , but they didn't .
From the number of failures I've seen here in the forums , they could be getting paid for their time .
Part number I got from the Newmar site, at that time, was 85866. You could call for current pricing , but be sure your sitting down when you ask.