ABS/ Speed sensor?

I have a 1999 dodge ram 1500, today while driving home, the ABS light along with the parking brake light illuminated. Upon investigation, i discovered that at speeds below 25, my speedometer doesnt work. though some research i found that the speed sensor is bad. it there a way i could replace this my self or is this a dealership only kind of fix. also i was curious where the speed sensor is located? thanks