Hi, Guys. My son has this ATV that has a sorta universal joint coupling between the engine and the transmission. It uses 2 metal plates about 4 inches in diameter and about 20 thou thick to act as the flexible part of the coupling. His parts have some stress cracks. I can make new ones, but I don't know what material they should be. Left to my own devieces, I'd probably use 1070 or 5160, but my son says that the parts are only slightly magnetic, and, even though they are 40 years old, there is no rust at all on them, whereas plenty of the other parts of the machine are quite rusty.
I'd hate to make new parts and then have them fail, so I'd apprreciate any input I can get