If you want to save some time and $, cut a piece of paper and wrap it around the tube and mark it to get the circumference. Unwrap it an measure it, divide by 3.14 and you have your diameter.
I had gold Zokes on my 2005 TE510 but they had machined and anodized lower mounts at the bottom of the tubes. Like these
https://www.ebay.com/itm/2005-Husqva...ZaWQ9Q&vxp=mtr