It IS missing too many details. Heres the trick that I somehow forgot.
There is a double plate at the back of the 6v motor housing. It looks REAL difficult to get out. I think its riveted in if I remember right. You have to take that out. GUT the entire case of everything and the motor that I put in the article is not too long. Fits perfectly.
If you are into fabrication, the other idea is to take TWO 6v motor housings and lengthen one of them to suit. I didnt have to do that. That was why I was careful to put the part number of the motor there. Then again, manufacturers change their specs all the time.