The only thing holding it together now is the motor drive shaft tubes. If you look at the motor there are two screws between the three tubes where they attach to the motor. Remove those screws and the two halves should come apart. Remove the bolts that hold the transmission to the frame, I think there are three that go through the center of the case. The transmission case is is riveted together along the outside, those need to be drilled out to separate the halves.
H