The other major problem in this conversion is that the AWD rear struts sit at a much different angle than the FWD struts, though they both attach at the same point on the car. This is because the FWD struts attach to the subframe right behind the wheels, precisely where the rear axle sits on an AWD car. The AWD struts attach further back, and so are slanted towards the front of the car whereas the FWD struts are almost vertical. This causes a problem, but one that can be worked around.
A comparison between the two struts and their respective mounting points. On the left are the FWD struts and on the right are AWD.
The difference in angle is subtle, but important. It becomes very obvious when the AWD strut is actually alligned on the FWD car.
To correct this, I installed a tall rubber suspension bushing on the front bolt of each strut. The strut actually sits on this bushing instead of its stock location, and the bushing helps damp vibration in addition to supporting the load. To help reduce noise, I also put a rubber washer on the rear bolts.
The stock nuts were slightly too wide, and could not go low enough to bite the threads of the front bolts. So, I had to replace them with these. They worked wonderfully, and the struts now sit securely.
I considered making a full rubber spacer to correct this angle, but after examining the setup I chose to use, the cost of full spacers didn't justify the added support. After over 400 miles of driving, there was no deformation or visible stressing on the strut towers, and the rear suspension absorbs bumps as it should.
When I went to have the car aligned, I found out that the struts sit a little bit too high, and as a result, the rear wheels are cambered inward farther than can be adjusted. To correct this, I had to add two washers to the top of each strut. This raised the strut slightly, and pushed the top of the wheel out, in line with the bottom.