I am currently reading Igros Ramchal published by Machon Ramchal (Rabbi Mordechai Shriki). One of the first letters in the book (ג1 on page יב) is from the Ramchal to his Rebbe, Rabbi Yeshayah Basan while the Ramchal was taking a bit of a vacation in a small city north of Padua. In this letter, the Ramchal explains a difficult Tosfos in mesechet Yuma. This letter has gotten me very excited since this is the only material I am aware of where the Ramchal quotes any source besides Chazal or Tanach. Not only that, but this is the only material I am aware of where the Ramchal "shows his work" so to speak, meaning that he shows how he arrived at a certain conclusion or, said a bit differently, how he learned something.
Because of the 2 reasons above, I am very interested in seeing the original manuscript to verify that the text I'm working with is accurate. Does anyone know where I can see the original manuscript?