You are correct about the location of the rear main. Park the car on a clean spot on your driveway at night. If you come out the next morning and see a puddle of oil under the car then you know there is a leak.

Considering the very low mileage of the car and the information in your last post about how clean your flame trap was I think your rear main should be good for a long time. It will last anywhere from 150-200K depending on how good the maintainence is.

Another way to keep things in good shape is to use synthetic oil. Flame trap accumlation is virtually eliminated, engine wear is reduced, mileage will go up maybe 1-2 MPG, your significant other will love you more, etc.

My engine has 246K on it with 15K on the rear main. I started using synthetic when the seal was changed. I had a lot of varnish on my camshaft that was gone when I changed 2500 miles later. Mobil 1 or Amsoil are the preferred oils, there is a wealth of information in the archives.