1980 cj 258...interchangeable with 1983 Eagle...was just curious what kind of issues i would run into?
Should be fine. However make sure it does have the axle mounts. Also only an eagle pan works with an eagle. I know first hand a concord will not work no matter how close it looks.
Make sure it's late enough in the year it has the front differential mounts, or that you can make a reasonable facsimile with some metal. I know some early Eagles as well as 4cyl models had a different mounting setup.