- Partial or absolute Thomasine priority (it all began with the Gospel of Thomas; you can thank Martijn Linssen for providing a persuasive argument for this)
- Johannine familiarity and derivation from the Gospel of Thomas.
- An older version of John (proto-John) contemporaneous with the middle-era gospels, namely Matthew, Luke, and a redacted/synoptically harmonized Mark.
Here is a tentative chain of transmission:
0. Gospel of Thomas (at least an old form of its logia; dually written in Aramaic & Greek, as Linssen as pointed out)
1. Proto-Mark
2. Gospel of the Lord (proto-Luke of Marcion) and proto-John
3. Matthew, Luke, and Mark (harmonized)
4. John (harmonized)
5. Acts
It appears that the gospel tradition took off with proto-Mark, inventing narrative befitting of the sayer of the Thomasine logia, with Lord/Marcion and proto-John developing in their own unique ways:
- Lord/Marcion mostly elaborating upon proto-Mark, incorporating some more Thomasine logia and, possibly, wholesale inventing the passion narrative.
- Proto-John elaborating upon Thomas (and, oftentimes, arguing against it) within the model of the proto-Markan narrative.
- The failure for Christianity to catch on with the Judaeans, and...
- The general want to disassociate from the troublemaking Judaeans after the continual wars with the Roman Empire
Anyway, here are some general portions that I've discovered claimed as earliest:
- Of the prologue, only John 1:1-5 is primary
- According to Kari Syreeni in Becoming John: The Making of a Passion Gospel, the original version of John ended at chapter 12, with the passion narrative added later based on the synoptic materials. In this case, the story wraps up with the entry into Jerusalem, discourse over being glorified and "lifted up into heaven", and a summary of the teaching. Syreeni also claims that there are remnants of proto-John in chapters 14-17, and then everything from 18 onwards was added later. In that case, the story would end with the farewell discourse (and perhaps a glorification/transfiguration/ascent/apotheosis instead of the passion narrative; Giuseppe has done well in pointing out that the earlier version of Mark may have ended with the transfiguration as something like an ascent).
- Raymond E. Brown's similar structure of the Book of Signs (John 1-12) and the Book of Glory (John 13-21).