Hey folks !
Just to make some clarification, RUF is very much in business as Catmandu pointed out.
Darrin can and still sells Thetford cassette toilets and parts. He's got two on order right now for customers.
Just FYI regarding Seitz windows, he's stopped dealing with them, because at the end of the 2000s, Seitz could not figure out how to ship windows to him or any of his customers without more than 50% of them arriving broken
If anyone is interested in contacting Darrin, however, please do be patient as I do believe he is now also using part of his ranch for some sort of long range rifle training and shooting competitions, so he might be a little hard to catch.
If I can be of any help, please feel free to send me a PM or email...