Magnum Gasket issue

Oil Pan Interchange
At the bottom end, the Magnum engines all use the LA-series 360 rear oil-pan relief. Any 360 oil pan will bolt to a Magnum. However, a non-Magnum pan cannot use the Magnum one-piece oil-pan gasket, as the early LA-series pans are notched at each side of the rear relief, while the Magnum is not. A non-Magnum pan will require the LA-series 360 oil-pan-gasket set.

Read more: http://www.hotrod.com/techarticles/engine/hrdp_0804_small_block_mopar_engine/#ixzz39YlzBZqf

now......okay if you take a hammer and flatten out the two steps (LA oil pan) it seals just fine and you can use one piece gasket. It is not hard I did it with a body dolly and hammer in about 5 min. acpat