Manual valve body 727 - 3rd gear won't engage under full throttle

Trailbeast, not sure what you mean by half done?

Kim, yes and no on the just built. This was a swap the guts into a different case build. It worked flawlessly prior but due to a case that had cracked, I had to swap the internals into another case.
Can you elaborate on "adjust your manual valve"? What would you surmise could be left out, or installed wrong?
Pretty sure nothing was left out, and it will shift into 3rd under light load. It is very much a mystery as to why it won't physically shift into 3rd under full throttle.