can i replace my np231 with a np242 will it work with my 1990 stock auto trans in my xj

my 231 is junk and need to replace!

You'd do better to stick with the 231 as there's more aftermarket options available for it and alot of reviews around the web say that the 231 in a jeep is better than the 242's. The 242 will give you fulltime 4wd and unless you live where it gets alot of snow isn't really needed.

thanks for the advice!