Y' kiddin' me?
Rear shock replacements on a 142 are one of the easiest jobs to do on the car.
Why would you need to remove the rotor backing plate? You can remove the shock's lower nut [49] on the lower trailing arm easily with a socket or a spanner.
At the top, earlier 140s have bolt [43] and washer [44] - the bolt screws into the body.
74+ has bearing bolt [43A], washer [43B] and nut [44A].
At the bottom, the shock's bushes [46] sit over the outside of the lower bearing bolt [47], which is attached to the trailing arm [15] through the spacer [45] and a [49] nut. So all you need to do to remove the lower side of the shock is remove [49], [48] and [46], then remove bolt [43] at the top, and the shock is freeeeee.
Torque specs are in the Green Book, which is in the Oz Volvo Technical Library - 140 and 164 setups are identical.
Edit: technical archive is at https://ozvolvo.org/archive - mod.
