P100's have been around a while. They usually come in 'soapbar' form.
I have them in my Les Paul Junior and they are sonically very different to a Jazzmasters single coils.. higher ouput, less noisy, more bass, more mids, etc.
I'm not sure if a soapbar will fit in a Jazzmaster without routing but a normal humbucker will. I have a DiMarzio 'breed' in my Jazzmasters bridge position, the cover and foam hold it in place so there is no need for screwing.
Make sure you buy F-spaced though, or the pole pieces wont line up with the strings.
