Remove the old one, then buy a new one. It's not a Maxum specific part. Dripless or stuffing box? Dripless should be replaced every 5-10 years. stuffing boxes need to be repacked. If you don't know when they were done last, then I would do them all at the same time.
On an 18 year old boat, there is a high likely that the stuffing box/dripless and cutlass bearing are all original. They are rarely maintained within the suggested service intervals.