1-you will need a 9mm barrel and probably have some fitting in the hood and maybe the lugs
2-you will need to fit a barrel bushing
3-you may have have to replace extracor or tune or maybe not.
4-you may need new ejector,most likely not.
5-you may need new mags. or not. 9mm will sometimes work fine out of 38 super mags. but not the other way.
6-you may need to replace springs, or not. some of the hotter 9mm loads are close to 38 super.
besides the barrel and bushing everthing else will be trial and error.