How do you know witch one will work I am looking at the shimano LX-FD-T 660 witch is the top swing and the LX-FD-T 661 witch is the bottom swing I have a 26,36,46t chain ring setup I am using friction shift only witch one will work better they are both 9 speed Derialleur.Or will either one work well with my setup the rear cassette is 11,32t shimano.Thanks for any info.