when i applied to prelim years for the 2-3-4 programs, i used the same personal statement and same letters. i used 3 er letters and 0 medicine. one attending told me (he is at a 2-3-4 program), that they (the prelim programs) know that you aren't going into medicine so they don't care if you will make a good medicine resident. they just want to look for people who will work hard, get along with people, not cause problems for the year,etc. if you have good letters, then i would go ahead and use them regardless of who wrote them.