Hello,
I did a quick search and it seems Monroe makes a replacement strut, readily available from your local auto parts store.
Monroe part # 71798I might add, RockAuto has a sweet deal on them right now....they have 7 left in wholesale closeout.
Go to
http://www.rockauto.comClick start.
Choose Oldsmobile, 98, 1991
Under suspension, choose strut assembly
They're selling for $33.79 each, it's at the top of the list.
Even with shipping it ends up costing what you would pay for one strut at your local auto parts store (about $90).
One note, the struts themselves have no sensors or electronics built into them. The ride height sensor is mounted on the rear RH side of the frame above the lower suspension arm. The sensor is mounted to the frame and it has an arm which is connected to the control arm. This is how the computer knows how loaded down the trunk is and sends a signal to the air compressor to fill the struts with more air or release air.
TOC Admin
Brando