hi, i do my own conversion, as fortanate to have a miller and lathe, the differance is amazing, i use the steel outer seal, and a drop of loctite 601, i sprint a norton navigator with a a10 plunger engine in it, good fun. blew it up once due to the rubber backed seal blowing out and hence no oil to big ends, the steel backed one goes for ever. smoother, quicker of the mark, real differance