How to in install the oil pump drive O-ring?

Please warm the O ring to 150 degrees, this will help you stretch it over the oil pump drive housing. Also check out the images below for more instructions on the oil pump. Please upload a short video of the problem if these instructions do not help.

Yes that part was helpful but how to remove oil pump drive unit in order to install o ring?
Thank you.

You need to remove the mounting bolt and hold it down first, then use a flat blade screwdriver to help wedge it under the bulkhead of the drive. If you can't get it to move sometimes the unit can get stuck because of engine sludge.