Why did some MB300 chassis vehicles get regular 8-lug wheels up front, while other MB300s got the extended hub and a dually wheel? Here are two pictures showing the different wheels I'm talking about. Our MB300 has the regular wheels up front, and it seems like a pain in the butt, because if you get a flat in the rear, you have no spare tire, because the spare that came with our motorhome is for the front only. It should be possible to add the hub extensions up front, right? Is there more to it than that, and where do you find the hub extensions, because I've looked online and have only been able to find one for sale on eBay. Does anyone know the part # I would need?