I'm looking for a new diff for my 450SLC as the one in it is clicking and finding a w123 parts car is easy enough. However if I take out the 210mm diff and put a 185mm do I need to change the axles or driveshaft? Has anyone used a w123 diff in a r107? The reason I am bothering to do this is I want at least a 3.07 if not a 3.46 rear end. The taller ratios are easy to find in a 210mm housing but would make the car into a dog with a 3 speed and 4.5.