if it is the inner, you can do just that boot. but, since you have to pull the axle anyway, it would be better to do both. Just pull the axle out, cut bands on inner, remove inner end, take snap ring off of shaft, remove tripod and clean the needle bearings real good. Put new small clamp on, put boot on, install tripod and lube after you slide the end onto the tripod and reboot.
put small amount of grease on retainer that slides in diff to hold in place for easier installation.