I asked myself the same question a little while ago. What I found out was that all CM400 models and all CB400 twin models with the same engine and similarly styled frame will fit. I suspect that the CM185 tanks might fit, as well as the 450 Nighthawk and the 250 Rebel.
I'm not sure about the 250 Nighthawk or CX500 tanks, but maybe worth a try if you find a really great deal.
Alan
