I want to replace Blacktop Broadtrons in my 5220 with GFS Mean 90's or some kind of soap bar P90. Do I need a special mounting ring or is this an easy swap out? Any suggestions would be appreciated Thanks.
Welcome to the forum @forrealalexb. Even though I have that guitar, sorry I can't help with your question but some should be along shortly to give you an answer.
The G5220 has Broad'Tron pickups that have a format of their own, large than the usual Gretsch pickup format like the HD FT, BT FT, etc... See below the difference in size. covered by plastic film is the Broad'Tron from a G5220, the other being a Black Top Filtertron having the usual Gretsch pickup dimensions :
While a direct swap is not possible, if you change the Broad'Tron bezels for regular ones, you are done for any Gretsch-sized pickup. Maybe you will have to drill some holes for the fixation screws, though, but it's nothing unusual...