SRAM 10 Speed XO Rear Derailleur with 9 Speed Gripshift

[jackster57]

I am wondering if I can use a SRAM XO 10 Speed Rear Derailleur with a pair of 9 Speed Grip shifters / 9 speed chain and cassete? I believe the pull ratio is the same, so if I set the limit screws correctly I should be able to use it as a 9 speed derailleur, correct?

[crohnsy]

No. The ratio is different. They are not compatible.