You should be able to. Might be worthwhile to remove the front driveshaft to get a little better access. Remove the nut holding the lever on, remove lever, use a slim pick to remove the nylon outer washer/bushing and then the o ring. Clean area apply some petroleum jelly to the new O-ring and slide on, followed by the nylon bushing, install the rest of parts.
Also make sure the 4wd indicator switch isn’t leaking, or in my friends case, forgot to install the switch or a plug and wondered why it was leaking… It’s located such that if it’s leaking it will be inline with the shift shaft.
