I'm working on a design and have prototyped transformers a while back but I just finished the board design an am about to order ordered parts. I was using the LNK420EG. It looks like this part been replaced with the LYT4218 for low line appliations? My design is based on RDR-290 and other LNK420 app notes. My design is a low line non-dimming 75W design. Hopefully the transformers will not have to change.