I just purchased a set for my BX1830. The paperwork shows a kit number of G 8100A. I included a picture of the installation sheet, I have a note on their about having 3.25” of threaded rod sticking out the back side of rim. This made the outside mounting flush. I didn’t want to cut any of the threaded rod yet.
Also, be careful with your Kubota dealer, one of my local dealers “needed to order” the kit for me and they were going to charge $175+tax. I called another dealer and they had a set in stock and I only paid $100+tax. The first dealer wanted to charge me (without disclosing) for the shipping costs....