I'm not around my boat to double check, hopefully someone else can shed a bit more light on the topic at hand, though I imagine a boat of your vintage will likely be a Classic Tilt Hydraulic Helm model? I'd obviously confirm this with another forum member, GW or SeaStar themselves before purchasing. That being said, they also appear to have a couple of replacement seal kits on their website. Is your unit something that can't be repaired? Unless the entire housing is cracked, I imagine it's likely a seal that is leaking?
SEASTAR HELM
www.bow.com