the short-c/f arms come with the lp.
u3549 front
u3550 rear
the short arms are way stronger because the webbing is beefed up. i would call any of the standard length arms obsolete at this point. they'll run fine, but they are brittle unless you run the medium flex versions, which have tons of flex.
stick with the above. if you're breaking them, you can go with the short-med flex versions.
u3551 front
u3552 rear