HELP ME PLEASE: RESTO BUILD SHEET & FENDER TAG ?'s @ Transmission

Actually, 904 is auto, while a manual 3 speed is a 903. Just found that out. Google is a wonderful thing.
There were other 3 speed manuals also, but most sixties /6's and some lo-po V8's had the 903. I think your car is in original state bro. It looks like a fun project.....I'm jealous.