From Maximum Motorsport'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."