Suspension Rear Upper Control Arm Question

MM rear upper arm has stiffer rubber in it than a stock one.

If I recall correctly the MM arms (and lmr) were basically sn95 arms. In fact, they could have just been sn95 arms entirely. Like stated above, they have stiffer rubber.

This is from MM’s website:

These Ford rear upper control arms are direct replacements for the 1979-2004 Mustang (non-IRS) control arms. They will restore performance lost to old and deteriorating rubber bushings. These control arms have the stiffest rubber bushings available, and are much stiffer than what came originally on the Fox chassis Mustangs. Although Ford Racing Performance Parts claims their bushings to be "twice as stiff" as stock, our testing has shown that while they are much stiffer than Fox chassis bushings, they are identical to the 1994-04 bushings.
While for 1994-04 cars these control arms offer no improvement in performance, as they do on Fox chassis cars, they are a great value when replacing arms with damaged or aged bushings. Because rubber deteriorates simply from age, after several years the control arms are ready for replacement.

I think you’ll find the MM parts aren’t much different than those moot for the sn95’s.