Yeah,I made the conversion...As I said ,om621 don`t have any relais so I don`t seem the point in installing one,just got the 4 plugs ,connected them the right way -et voila! It works.The ballast resistor prolongs the glow time,so it`s gonna be replaced by the 50A strip fuse from w123 I`ve already ordered...Hmm,I don`t see anything that could go wrong,and why do I need the relais when I just can cout several seconds???Thanx for the replys,guys!