Hello, since the 3.1 does not have a distributor O ring, I assume you mean the O ting that goes on the oil pump drive cover, which sets where the distributor would be if the car had one? If I remember correctly, you may be able to access the cover by removing the exhaust cross over pipe and then removing the hold down bolt. The cover will be hard to get off because the O ring will want to stick and hold it in place. Sometimes a large pair of channel locks or sometimes a small sharp chisel inseted in the edge and tapped on with a hammer to get it to lift a little. The only thing holding it is the hold down bracket with the one bolt and the O ring itself. If you can't get to it by removing the exhaust cross over pipe, instructions from GM service manual are below. Thanks
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten Tighten the oil pump drive clamp bolt to 36 N·m (27 lb ft).