Anything that is FJ55 specific will be hard, expensive or impossible to get. Anything that the FJ55 has in common with the FJ40 you’ll have a bit of easier time finding.So what kind of parts are the hardest to get?
Post some pictures of your old 55 when you get a chance or a link to the sale add, most guys here know exactly where to look for rust and other potential issues and might be able offer you some advice.