Randy mckinney Posted October 27, 2013 Share Posted October 27, 2013 1985 rd688 12 speed maxi torque. What oil is recomended for this tranny? Also what can cause this tranny to lock up when shifting from low to rev. Flip the switck back an forth it comes out of gear and ur good to go till next time u need rev. Any ideas on what can cause this? Mack said to change filter on air going to tranny so i did and no change. Then they told me to bring it to them and they could find the problem for what im sure would be a big bill. Quote Link to comment Share on other sites More sharing options...
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