Jaahas, löyty vähä lisää tietoo:
http://www.arboristsite.com/chainsaw/149815.htm
"Looking at my IPL for the BR 500,550, and 600 models I see:
cam wheel- 42820301801 (BR550 and 600) and 42820301802 (BR500)
ign module- 42824001301 (BR500) and 42824001305 (BR550 and 600)
muffler- 42821400602 (BR500) 42821400603 (BR550 and 600)
carb- 42821200600 (BR500) 42821200602 (BR550) 42821200601 (BR600)
fan housing inside- 42827004100 (BR500 and 550) 42827004101 (BR600)
fan housing outer- 42827010701 (BR600) 42827010700 (BR500 and 550)
fan wheel- 42827003400 (BR500 and 550) 42827003403 (BR600)
blower tube kits are different for each model as well
So it looks like the differences between the 550 and 600 are the carb, fan housing, fan wheel, and tube kit"