I have got a 761 crank and it has a spacer at the back of the crank spider. Looked on the shimano website and the 760 does not seem to have one.

I wondered what the difference was as I wanted to take the extra spacer out as I think the chain line is wrong with the spacer and when I am on the middle front big rear the chain complains. Took the spacer out but then the crank is too long. Is that what the difference is between the 761/760 and would it be ok to put the spacer on the non drive side arm?