I just rebuilt my transmission a week ago because the sunshell snapped, and also wouldnt shift into 3 or 4. Now that i have back in my truck, reverse is fine, but doesnt feel like its shifting from 1-2-3 and revs high. I can hear it down shift to first when shifting manually. and will move in manual 2 and 3 but revs high. any ideas as to what the deal is?

 

Sounds like your inlimp mode you sure the conector is seated right and you didnt pinch any wires?

 

As mentioned, default mode is 3rd gear w/ no power....check the fuses as well as the trans connector and wires......

 

I reconnected the trans connecter and all gears now work, but 4th gear is still slipping i think. im at 2500 rpms when doin 60, is this something will overtime fix itself since the transmission was just rebuilt? and also 1 doesnt shift into 2 until rpms are around 3000, sometimes i have to let off gas to shift.