There were a few different versions of this pickup. Most you see for sale were removed from lapsteels, so the pole spacing is way too wide (57mm) for guitar. The other common one has no pole pieces. The no pole piece version has a completely different, non P-90 type tone. It is much cleaner, not bad, just different. My version is the guitar version and has 50mm string spacing.
Unlike the original I am also making a soapbar version. It has the same footprint as a standard P-90; however, it just has less rounded edges so there might possibly be some fit issues depending on your pickup route and the thickness of its finish. It has fit in every soapbar route I have access to.
Lastly I now make a Dogear mounting option that will fit in a standard Gibson style Dogear route. It has the proper recessed bracket for a neck and bridge position for example a Epi Casino. If you choose this option you will need to get a Dogear ring.