The Th400 is brand new and after a few passes it wont go to third, More less 2ND gear is where 3RD is. So when im going WOT its first, then when i reach for second it wont shift. so i ratchet down again (to 3rd) but it goes to 2nd(or so i think, it may actually be third). WE have checked the linkage a million times and looked over everything on the shifter. Any more Help before i pull this trans out and have it fixed under warranty?

 

Unhook the shifter completely and see if it shifts through the gears.
A misadjusted shifter on your part is not cause for a warranty repair.
I would diagnose the cause before condemning the trans, and if the trans is hurt due to a misadjusted shifter, it isn't the builders fault.

 

Make sure the vacuum line is connected

 

Vacum line? its a th400 with a Reverse Valve body and transmission specialties trans brake. NO VACUM