Is any one able to give us an understanding why this may have been cut.
Accident damage?

Hi Reeni,
not sure as pics aren't close enough for detailed analysis. 
If that's you taking pics UNDER the car, please double check with Dad that you're in no danger of being
hurt by car body falling and hurting you. 
Years of seeing bad accidents in homes and workshops begs for a "backup system". In this case here,
such as ropes thru the side cavities and tied back to ceiling. 
Good mechanics ALWAYS place 2 jack stands EVERY TIME they jackup a car; even if it's for a "quick going-under".
Broken bones and death are PERMANENT; cars can always be fixed !

Hi Reeni,
 
This section was used only in the early V6s (first couple of months in 1970) and 4 cylinders.  The first V6s were from modified 1969 4 cylinder shells.  Later V6s have a different shell (can anyone expand on this).  From factory this section is continuous.  This was possibly cut to allow easy removal and installation of the gearbox.
Continue with all your good work.
 
Regards
John 

4cyl Autos, and early (all) V6's had this chassis piece, it tends to foul on the linkage rods most likely why someone cut a section out of it