My coolster 3125xr8-s chassis broke and only one I can find is a taotao 125d and for the life of me I can't find the a-arm and swing arm measurements so I can know if they're compatible or not if anyone can help me out I'd greatly appreciate it. My A-Arms Are 6in from bolt hole ends

 

Have you checked vmcchineseparts.com? They have photos and descriptions with measurements for many a arms. Good luck.