Tony,
That is the correct gearbox for the carrier. There is an extension off the rear diff which houses the speedo drive. There is no "Foot" to support it like the Aussie carriers have.
You can find reference to the CAD drawings here...
http://www.mapleleafup.org/forums/showthread.php?t=9261
A word of caution on these drawings...I had purchased a shutter kit from the same fellow a few years ago only to find out the shutters were not even close to the originals on my mk I. Looked close, but thats where it ended. I suspect you may find the same problem with these drawings.
The rear axel/diff is just a standard Ford 3ton split rear diff assy.