Today I was kneeling between my 85 350X and my 06 Kawasaki KLR650 staring at the 350X's master cylinder that I disassembled and cleaned. I was measuring the eye to eye width of my 350X's rear master cylinder, when I just happened to glance over at the KLR's rear Master brake cylinder. I notice that the master cylinder mounting holes were almost the same width and when I measured with a Micrometer I confirmed the holes were both equally spaced at 2 inches apart. Then I put the 350X's master brake cylinder next to the KLR's and I was surprised that the KLR's Master cylinder might work with the 350X!!! I temporarily removed my KLR's rear brake system to do a rough fit of the rear master cylinder and to my surprise it fit almost perfectly to the 350X's frame!!! The only problem I see is that the nipple that connects to the brake res. hose is bent 90 degrees instead of straight back. I still need to check out my friends 04 400ex's master brake cylinder. I will give an update once I figure out if the 400ex master cylinder will also fit..