I pulled out my old JBL brochure I got with my E140's 20 years ago, and was reading something about this kit to simplfy front mounting. What exactly did this kit do and is it still available? One of my problems with retrofitting E140's to newer bass cabs is that the rounded edge on the back of the mounting frame of the E140, makes the speaker too large by a smidge to front load without having to enlarge the circumference of the existing mounting hole of the cab. Would this kit be the answer to that?