I personally don't understand why it would be awkward at all?
They are there to sell both tractors and implements and you have a tractor that needs an attachment and they sell them and make profit on them. What is awkward about that? If they give you any grief about the kind type or condition of your current tractor they would IMHO be setting themselves up to be excluded from you becoming a possible future customer when you buy your next tractor and would also be cutting themselves out of any profit to be made on this implement and any others you might want in the future. Seems foolish to me to feel awkward and it also would seem foolish to me for any brand dealership to treat you like an outsider just because you don't have the brand of tractor they currently sell.
Sorry but if a dealership treats you better because you have their brand tractor than they do if you don't they are cutting you in some other way as well and surely are not worth dealing with to begin with.
I can walk into Messicks and buy an implement for a JD any day of the week and other than maybe a salesman pointing me in the direction of when/if you need or are thinking about a new machine don't forget to look at the ___ Kubota as they are a good machine and we have some nice deals going on now. I really haven't had a different experience than I did when I was at any other dealership weather I purchased from them or even had the brand tractor they sell. Remember you are the customer and its the profit they get from the money in your pocket that keeps them in business. This is true weather it be for a tractor, repair work, a new implement or even the used stuff they have for sale, so its up to you to be confident and demand to be treated with respect or they will not get that profit from you and you will also tell all your friends how poorly they treated you.
I wonder how many of those used other brands that dealerships have are there because they treated the customer poorly when they stopped in a Kubota shop to look at a new woods box blade for their JD or any other brand machine and were treated poorly because they didn't have their brand of tractor. DO you really think a smart buyer would return and buy a new machine and trade their machine if they had been or do you think they would go down the street where the other guy wanted to earn their business?
I would think if the dealership was worth dealing with they will do their best to earn your repeat business and I know many folks who purchased their second tractor at a particular dealership simply because they were treated right when it came time for repairs and new implements.
