Hi, I have a Makita 6201D cordless driver drill that takes a 9100 9.6V battery. I need to get a replacement but can only find the 9120 9.6V battery. They look pretty similar but I notice the 9120 has an extra edge/shelf/lip around it and I'm concerned that this may prevent it from seating all the way in my drill. Anybody have any experience with this? are they relatively interchangeable? Thanks