I have no idea if these would work of not, but at least worth looking into:
https://www.stretchcvboot.com/cv-boots/The way these stretch over the C-V, I'd have to think they would fit just about anything. Otherwise Rockford CV has a listing of sizes. Since I sold my coach, I can't measure to see if any these are close:
http://www.rockfordcv.com/pdfstore/Boot_Assemblies.PDFThe BT 136 is a number stamped on my boot. It was rebuilt by Rockford CV, however when they look up that boot number, it is way smaller than the CVs on our coaches, so I don't know why mine has that number molded into the rubber.
The CVs were made by Con-Vel and were an agricultural product. Con-Vel appears to still be around.
http://con-vel.com/ConvelBrochure%20(1).pdf