Peter.
Yes , the spring was replaced by a Hydropneumatic Strut.
And some 113.044 chassis had them.
The rubber pads came in two sizes, but all the parts houses I have dealt with only carry the thicker one ... Some guys actually double them up to gain a little pos. camber.
As far as the tire sizing on these , the Original 185R are a Euro
size, and although the profile is not stated in the size marking, it is 80 aspect ratio [ 80% sidewall/width ratio].
This is important to consider when converting/calculating to wider tires.
I have some 113s and have tried all different sizes, with the best luck right back with the stock 185R [ 80 profile].
They used to be available in the Mich X series , but no longer.. They are now available in the Mich Rain Force and I have found them to do nicely....