Four Speed (Most Adaptable/Easiest Install/74 Dodge Dart

What type of mods if I currently have an auto?

Quite a few like res1vw21 says. If you already have an automatic, I would suggest a 518. If I remeber correctly, there are several members here who have 518's and there are a few threads on the installs. There's tons of info on this swap all over the web, shouldn't be hard to find.