Lowboy Motorsports OBS Dually 3/4 Hub Conversion Arms88 98 OBS Dually Arms Lowboy motorsports 88 98 C3500 Dually Arms come with everything necessary to convert your OBS Dually with 22" or larger wheels and lay it on the ground. We have been doing this for 3 decades and know all there is to know about the big wheel Alcoa conversions on all dually trucks. You wont find a better deal. All of our dually conversion arms are built in house to assure that you receive the parts you want with the correct fitment