My J3 was manufactured as a J3F-65. A 337 dated 3-26-71 for wing spar replacement and recover of both wings and tail surfaces,, and for the removal of the Franklin engine and the installation of a C85-8 was sent into the FAA. The 337 section 8 further states that the installation conforms to the J3C-65 Type Certificate. The Type Certificate was approved by the FAA and is stamped by the FAA Engineering and manufacturing branch. A Standard Airworthiness Certificate was issued on 4/16/71 amended, with the manufacturer and model listed as a Piper J3C-65. Does this mean that I can now operate it under Type Certificate A-691 as opposed to Type Certificate A-692? The data plate had been over stamped as J3C-65.