I looking to replace the Chain drive on my Amt Kenworth/ Challenge transit mixer kit with a Hydrostatic drive uni,.( Hydraulic drive motor) for the drum. I seen on YouTube a rebuilt Amt Kenworth mixer truck kit with a scratch built hydrostatic drive with hydraulic hose line routing diagram. Using front hydraulic pump unit. I was wanting to go with behind can hydraulic pump unit. If not I'll go with the front mounted unit.