I am using Monark nozzles, I know Monark from Germany. I know people there. Nozzles are made in Germany (unlike Bosch). The 265 nozzle will fit the 617 and 603 according Monark. I know Bosch nozzles but the Monark nozzle is better, engine is quieter, much better idle and engine more responsive. Of course this is subjective somehow and the difference is obvious after you change nozzles...and there is a reason why you change nozzles. But still Monark I believe is the better nozzle. I am balancing injectors since many years and balancing within 3 bars is great. This gives a very smooth idle. You'll need a micrometer (3bars are probably 0.03mm +/- in shim difference) in order to do this and you need to work on shims. And after some time the nozzles will get out of balance and need to be rebalanced. I think MB is recommending rebalancing after 15K? Martin