Peter, could you please contact (or encourage the owner of J3578 to contact) John Emmett at john.r.emmett@btinternet.com He holds the records for the J types but I have to say that apart from the original factory production details the file for J3578 appears to be empty!
Hi Peter, The Register can only include information that owners send to us, so I have sent a separate email directly to you. Good luck with the restoration