Unfortunately not, they are different for a reason and they are different sized.
The YDK from a DC04 will fit the DC07, but a DC04 Ametek will not fit a DC07 (I tried once) it was just too small, the belt would keep slipping off the spindle because it just didn't fit right. The motor retainer is also there for a reason. It holds it in place. If the motor moves slightly, the spindle will be misaligned so the belt would keep slipping.
You can use any DC07/14 motor in it TBH, even brand new cheapo ones from £13