I have learned from experience that there are lots of things that Kubota offers as a factory installed item, that can not be ordered separately for installation later on. It might be the legal department sees this as a large liability issue, or it might be that it is so integrated into the machine that to add it later on would be like rebuilding the machine and would be cost prohibitive. It is alway less expensive to order it the way that you ultimately want it from he factory than it will be to try to retrofit a machine later on. In the 1960's it was commonplace to add air conditioning, power steering, power brakes, etc. to cars. Today, it can't be done because they are too complex and the parts all have to be integrated for everything to work as planned. Same for the modern day tractor. It is no longer just a cab, but part of a greater system that can't be modified after production. Dusty