The new seat should fit the old boat, but I'm trying to remember if the boats have been modified to strengthen those two holes. I think that I remember reading that Hobie upgraded the mold to strengthen the indents to prevent any possible damage from over spreading (or tightening) those plugs.
I might be mistaken, maybe someone else can correct me, but just be aware that if the boat didn't come with the new seat, it might not be designed to handle the stress of an overtightened seat plug.
Anybody remember if this is the case? The spreader plugs on the seats came with production boats starting in 2010. I'm not sure if the mold was changed in that year, or after, or not at all, I just think I read something about that.
Cheers for that, I'll wait and see if any further info is forthcoming