TH-350 problems

I have a Th-350 trany in my 78 firebird, it has about 9000 on the rebuild, anyway i cant get the car to go into 3rd gear. I can manually shift though all gears so i know its there, but in normal auto driving i cant get into it

Suck cause i just put 4.11's in and it revs reall high in town

Also how do i adjust shift points in the car