Wait are you just asking these doctors for letters without spending any time shadowing them? Any letter will be stronger if you spend time shadowing them. I wouldn't know where to find a pre-typed letter and I wouldn't know how to write one so it sounds like it is coming directly from a DO. Adcoms will know if you're just getting a letter to check off a box instead of actually spending the time to experience something and learn something new with the physician. I highly recommend you shadow one of those DOs for a few days then ask them to write you a letter. Otherwise, someone else who has written their own recommendation letter will be better suited to answer that question.