Charlie, I agree with Hugh. You need to unbolt the rear spring hangers that attach to the rear axle housing so you are able to move the axle and torque tube back. If you remove the rear tires, you are able to move the rear axle and torque tube further back creating extra room. This will allow the room to install the engine and gear box. Then you can move the rear axle and torque tube forward and attach to the gear box. I place blocks of wood under the wheels so the axle doesn,t drop down too low.