page 63 says in full:
2. Rear Axle and Suspension
The following components have been carried over from Scorpio:
1 = 7.5" rear axle assembly with viscous limited-slip differential. The ratio, 3.64 : 1, is special to the Sierra RS Cosworth
2 = Rear axle crossmember
3 = Fastening - rear axle assy to crossmember
The following components have been modified in comparison to the Sierra:
4 = Rear axle shafts
5 = Driveshaft stubs
6 = Lower suspension arm
7 = Shock absorbers (as XR 4 x 4)
8 = Coil springs
9 = Stabiliser assembly (as XR 4 x 4)[/b]
hope that helps