Clint, Yes the monte carlo from 1970 -1972 are the same as 1968-1972 chevelle and elcamino and all the A-body rears of this era.
Yes the upper controls are are one of the main swap mod items that will be needed. we carry them for 145.00 + the ride.
Next the mod would be the spring perch mounts centered on the axle tube tops.
The lower control arm pockets will be close but could be an issue. the shock stud will be at a slightly different angle and could need so adjusting also.
NOW obviously this will all depend on how well you want this rear to work and what you expect it to ride like. Remember this will not ride like the original rear did because it was never design to fit the application. It is a cheaper way to get a better rear under the car.
J D Race.com does sell many versions of htis rear at a lower cost than a Moser or Currie or Strange using used parts from other differential to make one rear stronger than a 7.5 easy. All the mounting points will be as stock except for the upper...YOU will still need the upper control arms to get the suspension to travel properly and true.
The lower and spring perch and brakes etc will all bolt right up like stock. All the mounts are GM original components. Please check http://www.jdrace.com
front page and click the new product in the NEWS section...it will take you to all the new products section.
We also offer HOUSING AND AXLE PACKAGES TOO...
Good luck on the choice of the rear. we will always be here to help in what ever you choose. Jim