there is a company called power trax they use the open carrier and use in the place where the spider gears are. you don't have to take the unit out and don't have to wory about shimming the case. it is availible at jegs or summit for around 400.00 alot better than setting up the back lash. this came out 2 days after i put my eaton posi from strange enginnering. and was still trying to get the back lash set right. it still ain't, 2 years later but hasent blown up yet.