From Magnumswaps.com
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Oil Pan
Magnum engines are factory equipped with a truck-style rear sump pan. If you’re installing the engine in a truck, no problem, but for installation in a car, you need the mid-sump standard car pan for a 360 engine. The Magnum uses a different gasket than the LA, but the good news is that you can use one of the nearly leak-proof one-piece rubber Magnum gaskets. More info here:
Tips and Tricks"
A lot more useful information on that site as well on a variety of subjects.