2001 Silverado not shifting automatically but manually in 1st and 2nd. Speedo doesn't work

I have a 2001 Silverado 5.3 4x4 that I just recently
purchased and the transmission doesn't shift in
drive(auto) you can manually shift it from 1st-2nd..
That's it.. It has reverse. Previous owner said the
T-case busted but it drove normal. He replaced
the t-case and now it shifts like this. He said he
replaced all the sensors on the new T-case and
then took the old ones off the broke one and still
nothing. ALSO THE SPEEDO DOESNT WORK!!
Any help would be greatly appreciated !! Thanks