Change a 904 to manual valve body

Or they use manual valve bodies because they are smart enough they don’t want the transmission shifting whenever it wants to.
Exactly! Had a rat motor in a 55 Chevy with an aggressive automatic valve body (could shift it manually, but not soften the shifts) It barked second gear EVERY time, whether I was next to a cop or not.
With the full manual in my runner, I could bark second and third if I wanted....... or shift 1-2 at ten mph and 2-3 at twenty, soft and quiet as a kitten. Or pull away from a light in high, if I wanted. When I was tired and it was late, I did that occasionally, just left it in third. Smart enough not to lug it excessively tho.