the original out put shafts are tuned doown to equal size IE the large end turned to 5 mm the the shaft is reversed in the housing the the outside end flatened on each side to except the pershing driven gear the the gear cases float on the gearbox with 2 tierods conecting the 2 together right and left the an ancore plate made of brass is attached to the lowwer rod the bolted to the tamtoy gearboxes this make every thing one piece and stablizes the outdrives and keeps them perfectly allined