Using Epoxy I first wire brushed the parts. Then I sprayed them with a lot of brake cleaner. They were spotless, carefully mixing the 2 part epoxy and applying it to the pieces. I let it dry 28 hours in a warm garage. Pressed new seal in it broke at the lip of the seal. Later taking upper oil pan from donor car I find the 1979 front seal is different then the 1980 seals or at least different than the 2 brands of seals I bought for a 1980. And the 1979 seal hardly requires any force to press in. Wish I new before I broke it twice and whoever broke it the first time and made such a mess of it had only ordered seals for a 1979 300sd instead of the correct 1980 seal. It would have saved so much grief.
But I learned that you have a car with no oil pan and the front on jack stands for a month there is still 2 full cups of black motor oil in the upper oil pan. That’s why our oil is always black that oil is not changed during oil change. It just dirties new oil instantly. You would have to drain oil with front of car in air then raise the rear of car to remove this at oil change. I thought this was a kewl thing to learn I’m going to try it when car goes again and oil gets black again and yes we used my moms measuring cup for the 2 cup from upper pan.