I don't think the earlier fuseboxes are the same as the later cabby's but not 100% sure. You can get one from GSF for a can as that's where I got mine, but they're not cheap, about £60 if I remember correctly.
All may not be lost though, how much has it burnt through ? You could pull out your fuel pump relay and sandpaper the connections and pop it back in and it should last a few months, I did that for a while on my old one until I fully replaced the fusebox. I checked the fusebox before I sold it and it had not even started to melt the new one.